SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VEETEBRATA. 

 a. Embryolog-y.t 



Development of Chondrocranium in Man. % — Dr. Giuseppe Levi 

 finds that the first rudiment of the chondrocranium iu man consists of 

 separate groups of closely ad pressed connective-tissue cells, the groups 

 indicating roughly the position of the future bones. There is apparently 

 no homology between these groups and the parachordals and trabeculae 

 of other mammals. The groups retain their separateness during the 

 period when they are converted into cartilage, and do not lose it until just 

 before the time when the chondrocranium reaches its highest degree of 

 development. The groups do not become simultaneously differentiated 

 in the chondrocranium ; the occipital appears first, then the sphenoid 

 and the auditory capsule, finally the ethmoid. Similarly, the process 

 of cartilage formation in the different areas does not proceed with equal 

 rapidity, nor, except in the occipital region, is its formation simultaueous 

 throughout the individual area?. The occipital region shows in its 

 development a striking analogy to a vertebra, aud in the author's opinion 

 consists of a distinct occipital vertebra, and a region probably composed 

 of fused vertebral primordia. The changes which occur iu the shape 

 of the skull during development are chiefly due to the changes of position 

 of the occipital and sphenoidal regions. Indeed, the floor of the sella 

 turcica may be said to be the only part of the skull which retains its 

 primitive position throughout the whole of development. 



Development of Villi in Human Intestine. § — Mr. J. M. Berry 

 summarises his results in the following sentences : — (1) The number of 

 villi in the intestine increases with the age of the embryo; (2) fully 



* 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 published, and to 

 describe and illustrate Instruments, Apparatus, &c, which are either new or have 

 not been previously described in this country 



t This section includes not only papers relating to Embrvology properly so called, 

 but also those dealing with Evolution, bevelopment and Reproduction, and allied 

 subjects,. I Arch. Mikr. Anat., lv. (1900) pp. 341-414 (1 pi. and 3 text figs.). 



§ Anat. Anzeig., xvii. (1900) pp. 242-9 (6 figs.). 



