574 RECENT ADVANCES IN SCIENCE BEARING ON MEDICINE. 



from plants others of our fellow-countrymen achieved from animals — 

 Wolf, Meckel, and our whole embryological school. As Harvey, Haller, 

 and Hunter had once done, so these men began also with the study of 

 the "ovuluni," but this very soon showed that the egg was itself 

 organized, and that from it arose the whole series of organic develop- 

 ments. When Huxley, after his return, came to publish his funda- 

 mental observations, he found the history of the progressive trans- 

 formations of the contents of the egg already verified, for it was by 

 now known that the egg was a cell, and that from it fresh cells and 

 from them organs arose. The second of his three famous papers — that 

 on the relationship between man and the animals next beneath him — 

 limned in exemplary fashion the parallelism in the earliest development 

 of all animal beings. But beyond this it stepped boldly across the 

 border line which tradition and dogma had drawn between man and 

 Least. Huxley had no hesitation in filling the gaps which Darwin had 

 left in his argument, and in explaining that " in respect of substance and 

 structure man and the lower animals are one." Whatever opinion one 

 may hold as to the origin of mankind, the conviction as to the funda- 

 mental correspondence of human organization with that of animals is 

 at present universally accepted. 



OMNIS CELLITLA "E CELLITLA. 



* * * The greatest difficulty in the advance of biology has been 

 the natural tendency of its disciples to set the search after the unity of 

 life in the forefront of their inquiries. Hence arose the doctrine of 

 vital force, an assumption now discarded, but still revealing its influ- 

 ence from time to time in isolated errors. No satisfactory progress could 

 be made till the idea of highly organized living things as units had 

 been set aside; till it was recognized that they were in reality organ- 

 isms, each constituent part of which had its special life. Ultimate 

 analysis of higher animals and plants brings us alike to the cell, and 

 it is these single parts, the cells, which are to be regarded as the 

 factors of existence. The discovery of the development of complete 

 beings from the ova of animals and the germ-cells of plants has bridged 

 the gap between isolated living cells and complete organisms, and has 

 enabled the study of the former to be employed in elucidating the life 

 of the latter. In a medical school where the teaching is almost exclu- 

 sively concerned with human beings this sentence should be writ 

 large: "The organism is not an individual, but a social mechanism." 

 Two corollaries must also be stated — (1) that every living organ- 

 ism, like every organ and tissue, contains cells; (2) that the cells are 

 composed of organic chemical substances, which are not themselves 

 alive. The progress of truth in these matters was much retarded by 

 that portion of Schwann's cell theory, which sought to establish the 



