THE SPIRAL TYPE OF CLEAVAGE. 233 



syncytium, and future theories of heredity must take this 

 into consideration." 



Even more directly, I believe, do the facts point to the 

 existence of such a structural continuity in the eggs of anne- 

 lids, mollusks, etc., where the division of a single cell at other 

 than the proper time would in many cases disarrange the 

 whole complex. The theory of prearranged harmony makes 

 too great a demand upon the cell as distinguished from the 

 organism to be within the limits of probability in this case. 



We have, moreover, as a basis for our belief in the continuity 

 of organization, not merely the results of comparative study of 

 the unicellular and multicellular forms and the inferences from 

 experiment, but there are a rapidly increasing number of obser- 

 vations showing the presence of actual protoplasmic continuity 

 between cell and cell. Observations of this kind upon plants 

 have been very numerous and include a wide range of forms. 

 (For the literature upon this subject see Zimmermann, '93, and 

 A. Meyer, '96). In animal tissue intercellular connections have 

 been found to be of wide occurrence among epithelial cells, 

 and from time to time, especially during the last few years, our 

 knowledge of these structures has been increased by their dis- 

 covery under many other circumstances. A brief resume of 

 the state of our knowledge at the time his book appeared is 

 given by Wilson ('97), concluding as follows : "As the subject 

 now lies, however, the facts do not, I believe, justify any gen- 

 eral statement regarding the occurrence, origin, or physiological 

 meaning of the protoplasmic continuity of cells ; and a most 

 important field here lies open for future investigation." 



It is interesting to contrast with Wilson's somewhat conserv- 

 ative view the opinion expressed by A. Meyer ('96) in a paper 

 published almost at the same time that Wilson's book appeared. 

 After a resume and discussion of the observations along this line 

 upon both the botanical and the zoological side, Meyer sums 

 up his views as follows : " So far as I can see at present, all 

 our knowledge upon this subject favors the view that proto- 

 plasmic connections occur between practically all cells of every 

 individual, that a characteristic of both the animal and vege- 

 table individual is the possession of one contimwus mass of 



