Page:Quarterly Journal of the Geological Society of London, vol. 32.djvu/281

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P. M. DUNCAN ON PARASITIC UNICELLULAR ALGÆ.
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23. On some Unicellular Algæ parasitic within Silurian and Tertiary Corals, with a Notice of their Presence in Calceola sandalina and other Fossils. By Professor P. Martin Duncan, F.R.S., V.P. Geol. Soc., &c. (Read January 19, 1876.)

[Plate XV.]

John Quekett described, in his lectures at the Royal College of Surgeons in 1851–1852, certain tubes or canals as being very frequently met with in the skeletons of corals; and in his Lectures on Histology, published in 1851, and which contained the subject matter of his previous discourses, he wrote as follows: "Confervoid growths also are very frequently met with in the skeletons of corals, as all these bodies possess animal matter which, decomposing after death, becomes a nidus for the development of confervæ; and hardly a section can be examined without exhibiting such an appearance as shown in fig. 78"[1]. This figure shows long, short, and almost straight canals cutting across the normal coral structure at different angles.

In 1859 Kölliker gave the results of his examination of some corals to the Royal Society, in a communication "On the frequent occurrence of vegetable parasites in the hard structures of animals"[2]. He said:—"All the genera of corals which I investigated contained parasitical fungi, viz. Astræa diffusa, Porites clavaria, Tubipora musica, Corallium rubrum, Oculina diffusa, Oculina, sp., Alloporina mirabilis, Madrepora cornuta, Lophohelia prolifera and Nullipora alcicornis. The fungi were most frequent in the genera Tubipora, Astræa, Porites and Oculina, the last three of which contained also many sporangia, which in the red coral were very scarce or wanting."

Before Quekett lectured, and contemporaneously with his and Kölliker's researches, Dr. Carpenter[3] and C. Wedl[4] investigated the corresponding tubes or canals in shells; and the last-named naturalist communicated a most admirable paper on the subject just before Kölliker came forward. Wedl described and de- lineated the tubes in perfect and in decalcified specimens of shells, and obtained a view of the parasite itself when removed from its nidus in Melania Hollandri under the effects of a dilute acid. He agreed with Quekett in ascribing the parasite to the Confervæ, and

  1. John Quekett, Lectures on Histology, vol. ii. p. 153. Parasitic borings corresponding to those noticed by Quekett were described by C. B. Rose, F.G.S., in fossil-fish scales from the Chalk and Kimmeridge Clay, in the Transactions of the Microscopical Society, 1855, p. 7. He figured them; and his faithful delineations show ramifying tubes and occasional globular enlargements. He attributed them to the operation of infusorial parasites.
  2. A. W. Kölliker, of Würzburg, Proc. Royal Soc. June 9,. 1859, vol. x.
  3. Carpenter, Cyclop. Anat. Physiol. art. "Shell."
  4. Wedl, Sitzungsber. d. kais. Akad. d. Wiss. in Wien, B. xxxiii. no. 28. Dec. 1858.