537 



SUMMAEY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOG-Y AND BOTANY 



(principally invertebrata and cryptogamia), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a, Embryologry.t 



Continuity of Elements in Early Stages of Blastoderm.| — 

 J. Cameron and R. J. Gladstone have studied this in early stages of 

 frog, chick, mouse, and other forms. They have come to the following 

 conclusions : — 1. In the developing blastoderm the nuclei, with their 

 contained chromatic material, ought to be regarded as the structural 

 units rather than the cell-elements as a whole. 2. There is an organic 

 continuity between the cell-elements of the developing blastoderm both 

 in Vertebrates and Invertebrates. (The authors have traced this con- 

 tinuity up to the three-layered stage in Mammals and in the chick 

 €mbryo, in the chorionic villi and in the placenta.) 3. This continuity 

 is in most cases primary, and not secondary (plasmodial rather than 

 syncytial). 4. Protoplasm may be differentiated into endoplasm and 

 ectoplasm. The nascent endoplasm forms a clear, highly refractive zone 

 immediately surrounding the nucleus. This merges into a more mature 

 endoplasm, which in its turn undergoes transition into a granular 

 ectoplasm. 5. The nascent endoplasm, the more mature endoplasm, 

 and the ectoplasm represent three stages in the genesis of protoplasm. 

 It is a well-recognized fact that the protoplasm of every living tissue 

 has a limited period of activity during which its vitality is constantly 

 being revived and rejuvenated by regulated supplies of nascent material. 

 The latter is apparently a derivative of the nucleus, and is discharged 



* The Society are not intended to be denoted by the editorial" we," and they 

 do not hold themselves responsible for the views of the authors of the papers 

 noted, nor for any claim to novelty or otherwise made by them. The object of 

 this part of the Journal is to present a summary of the papers as actually pub- 

 lished, and to describe and illustrate Instruments, Apparatus, etc., which are 

 either new or have not been previously described in this country. 



t This section includes not only papers relating to Embryology properly so 

 called, but also those dealing with Evolution, Development, Reproduction, and 

 allied subjects. 



X Journ. Anat. Physiol., 1. (1916) pp. 207-27 (15 figs.). 



Dec. 20tK 1916 2 ? 



