'PHYSIOLOGICAL UNITS* 89 



of reduced cells naturally suggests the probability or possibility 

 of fusion, and to us it did so particularly in view of what happened 

 in the case of certain ferns observed by Prof. Farmer, Mr. Moore, 

 and Miss Digby more than a year ago. Here the application of 

 suitable stimuli to prothallial tissue caused the nuclei of adjacent 

 cells to fuse, fertilisation and the production of the succeeding 

 generation taking place in some cases without any sexual elements 

 appearing." 



This change in the cells of cancer, representing an incipient 

 conversion of them into the forms of germ-cells, must be regarded 

 as decidedly adverse to the views of Weismann as to the absolute 

 distinction between the ' somatic-cells ' and the germ-cells and the 

 * continuity ' of the latter. His views moreover seem negatived by 

 multitudes of well-established facts concerning budding, ' regenera- 

 tion ' and repair of injuries generally, to which we must now turn 

 our attention. 



Our knowledge concerning these processes in various animals 

 has been greatly increased during recent years, though the power 

 of propagating themselves by buds and cuttings possessed by all 

 kinds of plants has long been thoroughly familiar. In some Algae, 

 such as Caulerpa, in Liverworts, and in Bryophyllum, one of the 

 House-leeks, this power is possessed to an extreme degree, so that 

 even minute fragments of such plants are capable of growing and 

 developing into perfect plants. While, as we are told by Dr. (now 

 Sir Wm.) Hooker,' there is " a species of Begonia the stalks, leaves 

 and other parts of which are superficially studded with loosely 

 attached cellular bodies," and " any one of these bodies, if placed 

 under favourable conditions, will produce a perfect plant similar 

 to its parent." 



In animals this power of repair is by no means so wide-spread — 

 which is only what might be anticipated having regard to the 

 increasing complexity of organisation met with in the higher types, 

 and to the fact that they are not mere repetitions of more or less 

 similar parts, such as obtains so largely among plants. Among 

 lower animal organisms we find the property wide-spread and 

 very remarkable. Beginning with ' unicellular organisms ' = ; it 

 is seen also among different kinds of Polyps, Medusce, Starfishes, 



' Report of Brit. Association, 1868. 



' See the Experiments of Balbiani with Stentor (pp. 40, 41) and the results of the 

 section of cells generally. 



