GENERAL CONCLUSIONS. 49 



nucleated Infusorian with a mouth leading into a central 

 vacuolated mass of protoplasm. 



The continuity between the various cells of the adult — the 

 connections between the nerves and muscles and sensory epithe- 

 lial cells, receive an adequate morphological explanation ; being 

 due to a primitive continuity which has never been broken. 



Herbert Spencer's view of the origin of the nervous system 

 may perhaps not be so far from the mark as at first sight 

 appeared. In any case the efforts to find out how the connec- 

 tion is established between the nervous and muscular tails of 

 the ectoderm and endoderm of the lower animals should be 

 transferred to the earliest phase of the embryo, i. e. to the seg- 

 mentation stages. 



Finally, if the protoplasm of the body is primitively a syn- 

 cytium and the ovum until maturity a part of that syncytium, 

 the separation of the generative products does not differ essen- 

 tially from the internal gemmation of a Protozoon, and the 

 inheritance by the offspring of peculiarities first appearing in 

 the parent, though not explained, is rendered less mysterious ; 

 for the protoplasm of the whole body being continuous, change 

 in the molecular constitution of any part of it would naturally 

 be expected to spread, in time, through the whole mass. 



In short, if these facts are generally applicable, embryonic 

 development can no longer be looked upon as being essentially 

 the formation by fission of a number of units from a single 

 primitive unit, and the co-ordination and modification of these 

 units into an harmonious whole. But it must rather be 

 regarded as a multiplication of nuclei and specialisation of 

 tracts and vacuoles in a continuous mass of vacuolated pro- 

 toplasm. 



At any rate I may safely say that, so far as the individual 

 embryonic development of Peripatus is concerned, the connec- 

 tion of cell with cell is not a secondary feature acquired late in 

 development, but ia primary, dating from the very beginning 

 of development. 



Since making these observations on the syncytial nature of 

 the cleavage and gastrula stages of Peripatus capensis, I 



D 



