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from what constituent of the proteid molecule it is derived. The other constituents of the molecule may perhaps furnish the antidote, or a poison antagonistic to that produced by the bacillus; for we know that poisons are antagonistic to each other—atropin and muscarin for example, We may even hope to find that the action and growth of the bacilli may be inhibited by certain substances, and then by injecting these substances into the blood, disease may be prevented, or if disease exists it may be arrested or cured. Is there not then, in this direction, much that should attract you and in Harvey's words "encourage you to search out the secrets of nature"? The changes seem so minute and inscrutable, sometimes so transitory, that amidst difficulties and disappointments we may often be discouraged and inclined to abandon the investigations. So it was with Harvey—"I found the task so truly arduous, so full of difficulties, that I was almost tempted to think with Fracastorius, that the motion of the heart was only to be comprehended by God At length by using greater and daily diligence I thought that I had attained the truth and that I had discovered what I so much desired, both the motion and the use of the heart and arteries." Reverently, earnestly and hopefully he continued his work, and he succeeded. Let us follow in his footsteps, gathering up the facts, and with minds educated and trained to reason upon the facts, let us try to penetrate further into nature's mysteries; thus may we be enabled to do God's work in the world, preventing and healing all manner of diseases, and so promote the happiness and welfare of mankind. One, whose memory is reverenced by all here, Dr Parkes, wrote : "In the scheme of Providence it may not be meant that man shall be healthy. Diseases of mind and body may be the cross he has to bear; or it may be the evil against which he has to struggle,
