580 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Attention was directed in the pupse to the wall of the pharynx, the 

 trachese, the saUvary duct, the hypodermis, the muscles, the rectal 

 glands, the visual cells of the ocelh, and the ocellar nerve ; and the 

 Malpighian tubes of adults were also examined. In general, it was 

 found that the sizes of nuclei in drones and workers were the same. 



Structure of Nuclei of Salivary Cells of Chironomus.*— W. 

 Faussek describes within the well-defined cell-membrane a nuclear 

 thread, consisting of an oxyphilous substance which extends all along 

 the thread, and of a basophilous substance which is arranged in disks. 

 The darker disks are filled with basophilous granules ; the intervening 

 areas are without them. Similarly, on the nucleolus there is an external 

 oxyphilous zone and a larger basophilous core. Details of the minute 

 structure are described and strikingly figured. 



Spermatogenetic Mitoses of Earwig.t— C. F. U. Meek has made 

 careful measurements of the metaphase spindle in the spermatogenetic 

 mitoses of Forficula auricularia, and he thinks that he has established 

 a dimensional relation between it and the volume of the cell. His 

 conclusions are as follow. 



1. The length of the mitotic spindle, i.e. the distance between the 

 two centrosomes at the stage of the metaphase when the chromosomes 

 are undergoing constriction in the equatorial plane, appears to be a 

 constant for each spermatogenetic mitosis of the species. The lengths 

 found are 6*9, 10*2, and 7*8//. for the secondary spermatogonia and 

 primary and secondary spermatocytes respectively. 2. The length of 

 the mitotic spindle at the conclusion of the metaphase, when the 

 daughter-chromosomes are ready to move apart, appears to be a constant 

 for each spermatogenetic mitosis of the species. The lengths found 

 are 7'1, 10 '4, and 8'1 ft for the secondary spermatogonia and primary 

 and secondary spermatocytes respectively. 3. The length of the mitotic 

 spindle in the earliest anaphase, i.e. at the moment when the daughter- 

 chromosomes have begun to move apart, appears to be a constant for 

 each spermatogenetic mitosis of the species. The lengths found are 

 7*3, 10 • 7, and 8 ' 3 /x, for the secondary spermatogonia and primary and 

 secondary spermatocytes respectively. 4. The ratio between the lengths 

 of the mitotic spindle at the conclusion of the primary and secondary 

 spermatocyte metaphases is almost identical with the ratio betw^een the 

 two spheres, of which the volume of the one is equal to twice that of 

 the other ; and the volume of the primary spermatocyte cell must be 

 equal to twice that of the secondary spermatocyte at this stage, because 

 no growth or resting stage intervenes. 5. The ratio between the 

 lengths of the mitotic spindle at the conclusion of the primary spermato- 

 cyte and secondary spermatogonial metaphases is almost identical with 

 the ratio between the radii of two spheres, of which the volume of one 

 is equal to three times that of the other. The initial volume of the 

 primary spermatocyte cell must be half that of the secondary spermato- 

 gonium, because the latter divides to form two daughter primary 

 spermatocytes ; but the large size of the last-named, observed at the 



* Arch. Mikr. Anat., Ixxxii. (1913) Abt. l,pp. 39-58 (2 pis.). 

 t Quart. Jcurn. Micr. Sci., lix. (1913) pp. 249-65 (1 pi.). 



