SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLiOGY AND BOTANY 



(principally invertebrata and gryptogamia), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a. Embryologry.t 



Maturation in Mus musculus.J — L- (TCiiach finds that two directive 

 mitoses always occur. ' In three-t'ourtlis of the cases observed only one 

 polar body was to be seen after maturation. The chromosomes of the 

 monaster of the first directive mitosis are tetrads. The spermatozoon 

 may enter the ovum between the first and the second monaster stage. 

 Most of the tail euters the ovum. Postponed insemination may hinder 

 the formation of the second polar body. 



Ovum of Bat.§ — 0. van der Stricht gives an account of the structure 

 of the egg of VespertiUo noctula during growth of the oocyte, matura- 

 tion, fertilisation, first segmentation spindle, and early segmentation. 

 There is a very clear difference between the first and second matura- 

 tion spindles. The chromatic segments of the first spindle resemble those 

 of many invertebrates, especially Thysanozoon. The figures suggest that 

 the divisions have the same significance as in Invertebrates. The 

 mitochondria of the oocytes are cytomicrosomes capable of various modes 

 of development ; they, and the formations resulting from them, appear 

 during the genesis of the plastic vitellus and the deutoplasm. 



Syzygy of Spermatozoa in Dasypus villosus.|| — E. Ballowitz finds 

 that in this Edentate the spermatozoa are very frequently firmly united 

 in pairs (" Syzygien"). What it means remains obscure. Similar 

 phenomena (not to be confused with spermatozoa with two tails) have 



* The Society are uot 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 Wiesbaden, 1906, 31 pp. (2 pis.). See also Anat. Anzeig., xxix. (1906) p. 494. 



§ Anat. Anzeig., xxvii. (1905) Erganzungsheft, pp. 17-24. 



n Op. cit., xxix. (1906) pp. 321-4. 



C 2 



