SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANiY 



(principally invertebrata and cryptogamia), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 

 a, Embryolog-y.t 



Influence of Radium Rays on Ova and Sperms. J — 0. Hertwig has 

 subjected fertilized ova of frog and axolotl to radium rays. During the 

 exposure, and for some time after, no effect is seen, but after a consider- 

 able interval the influence of the radium becomes apparent, always in 

 a very detrimental way, but varying with the duration and intensity of 

 the rays and with the stage of development reached. The differentia- 

 tion of nerve and muscle is much more affected than that of the more 

 vegetative tissues. Hertwig also exposed mature spermatozoa of sea- 

 urchin and frog to radium rays, and then tested their effect on the egg. 

 The spermatozoon induces serious disorders and finally disintegration in 

 the egg, acting like a virulent bacterium, and the disturbing effect 

 spreads from cell to cell with the chromatin at each mitosis. 



Polyspermy.§— J. Riickert discusses cases of frogs' eggs fertilized 

 by two or three spermatozoa, in which abnormal results may be avoided by 

 elimination of the supernumerary spheres. Polyspermy seems often to 

 occur in meroblastic ova, e.g., of Selachians and Birds, and pathological 

 results are averted by the exclusion of the supernumerary nuclei from 

 the segmentation area. In sea-urchin ova, with little yolk, the entrance 

 of more than one spermatozoon disturbs the fertilization process. In 

 the small space the expulsion of the centrosomes and their spheres can- 

 not prevent a pathological union of the pro-nuclei. In Urodela poly- 

 spermy may occur without disadvantage ; the supernumerary sperniatozt a 

 are not eliminated, but in some way destroyed or annulled. 



* 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. J SB. k. Preuss. Akad. (1910) pp. 221-33. 



§ Anat. Anzeig., xxxvii. (1910) pp. 1G1-S1. 



