782 SUMMARY OF CURRENT RESEARCHES RELATING TO 



as sperm-duct at one time, when its internal aperture is closely 

 applied to the body-wall, but when it carries ova to the exterior this 

 aperture is directed backwards to the posterior portion of the coeloin, 

 so that the duet is in some way movable. 



The author finds that picric acid is the best hardening agent for 

 Lingula, followed by picro- or borax-carmine as staining agents, 

 osmic-acetic acid being also a useful agent. 



Arthropoda. 



Claus on the Classification of the Arthropoda.* — Prof. C. Claus 

 answers the article of Prof. Pay Lankester,j" and points out Low his 

 proposed system differs from that of the English naturalist, and that 

 much of his system has been expressed in earlier papers and in his 

 text-books. Some of the results of Lankcster's investigation of 

 Limulus, as well as his hypotheses, are criticized. To this Prof. 

 Lankester rejoins,! maintaining his original position. 



a. Insecta. 



Origin of Cellular Elements of Ovaries of Insects. §— Dr. E. 

 Korschelt has a further essay on this subject, which owes its origin 

 to his having found that some of his earlier results were due to the 

 unsatisfactory condition of his preparations. Ho now states that, as 

 Will has asserted, the germinal vesicles arise from the nuclei which are 

 collected in large quantities at the base of the terminal chamber of 

 the ovary. The new results were obtained by the use of double 

 coloration with picrocarmine and hematoxylin, when the germinal 

 vesicles become red, and the other nuclei of a dark violet colour. It 

 may be concluded that the cellular elements of the ovaries of insects 

 arise in various ways, while the epithelium has always much the same 

 mode of origin. In all the forms examined by the author the nuclei 

 of the terminal filament and the indifferent elements at the tip of the 

 terminal chamber may be followed as far as the epithelium of the true 

 oviduct, without undergoing any remarkable change. 



With the ovarian and nutrient cells it is different ; in the Ortko- 

 ptera and in those Coleoptera in which there are several nutrient 

 chambers the conversion of the indifferent elements into germinal 

 cells takes place at the tip of the terminal chambers ; in Coleoptera 

 without several chambers and in the Hemiptera the germinal vesicles 

 appear to arise from small nuclei at the base of the terminal chamber. 



Origin of Colours in Insects. || — Mr. J. W. Slater adduces some 

 evidence to disprove Mr. Grant Allen's theory that the most beautiful 

 insects are such as haunt flowers, fruits, &c, and that carrion 

 feeders are, on account of their food material, the most ugly, or dull 

 coloured. The author mentions various species from the different 



* Ann. and Mag. Nat. Hist , xviii. (1886) pp. 55-65. 



t See this Journal, ante, p. 419. 



% Ann. and Mag. Nat. Hi'st., xviii. (18S6) pp. 179-82. 



§ Zool. Anzeig., ix. (1886) pp. 256-63. 



|j Trans. Entomol. Soc. Loud., 1886, pp. xix.-xxiii. 



