49Q POPULAR SCIENCE MONTHLY. 



of disease, and promulgated that doctrine, so bold for his time, 

 " Omnis cellula ab cellula " (every cell from a cell) — a doctrine 

 that will always stand like a corner stone of the temple of science. 

 The continuity of everything living expressed by this doctrine was 

 confirmed later on by the progress made in comparative anatomy, 

 so that the fundamental plan common to the type of vertebrates 

 could be traced to its last details, and it was shown that between ani- 

 mal and human structure the characteristic of distinction is not 

 absolute, but only relative. Of special importance in this connec- 

 tion is the proof that even the organ of mind — i. e., the brain — is no 

 exception to the general rule, and that it is built on a common funda- 

 mental plan in both man and animal. 



After all, not much had been gained for a philosophical view of 

 Nature and a natural explanation of generation, in its inception, by 

 the discovery of the cell as the primordial form of the organic 

 world, the cell itself being too high and complicated a formation 

 to be regarded as rudimentary. There was therefore a hiatus in 

 our knowledge which gave the opponents of the theory that the 

 world is the result of a series of changes governed by natural laws 

 a convenient ground for declaring the theory untenable and false. 

 But this difficulty also was removed by the discovery (likewise be- 

 longing to our century) of protoplasm, or the original primordial 

 substance, made by Max Schulze in 1863. This protoplasm, consist- 

 ing of shapeless organic matter, is identical with TIaeckel's cele- 

 brated monera, or those formless albumin lumps, those organless 

 organisms out of which the true cell only develops after a long 

 series of intermediate stages. And the moner itself, in all proba- 

 bility, is not the first step, but the ultimate product of previous stages 

 of development in the process of the transformation of the inorganic 

 into the organic. Naegeli's mechanico-physiological theory of de- 

 scent goes even so far as to declare the distance between the moner 

 and the true primordial plasma substance far greater that that be- 

 tween the moner and the mammal ! In the light of these discoveries 

 and the consequent conclusions, the much-ventilated question of 

 primal generation, which formerly was covered by impenetrable 

 darkness, no longer presents any difficulty in the way of scientific 

 explanation. 



Physiology. — In close connection with anatomy and the history 

 of evolution, which are occupied with the physical building up of 

 the organisms, stands physiology, or the science of the functions of 

 the organs. Here we notice, in the first place, the great discovery 

 made by von Baer, in 1827, of the ovum of the mammals and of 

 man, in its original place in the ovary. This discovery was soon 

 after followed, in 1844, by the elucidation by Th. Bischoff of the 



