ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 669 



carbonic anhydride, is able to effect saponification ; hence the interven- 

 tion of some other acid need not be assumed. 



General. 



Determination of Sex in Plants.* — R. P. Gregory has investigated 

 this question in connexion with the suggestion of Castle (put forward in 

 relation to animals only), that sex is an inherited character which 

 exhibits the Mendelian phenomena of segregation and dominance, and is 

 not subject to direct control by environment. Accepting the view that 

 the chromosomes contained in the germ-cells are the factors concerned 

 in the transmission of inherited characters, and also the hypothesis that 

 the segregation of characters in accordance with Mendelian laws is pro- 

 vided for in the reduction division, it was important to observe the 

 occurrence of that division. Spore-formation and divisions in the pro- 

 thallia were observed in Osmunda regalis, and it was found that a true 

 (qualitative) reduction takes place at the time of spore-formation. The 

 problem of sex-determination is complicated in the higher plants by 

 alternation of generations ; and in the higher Cryptogams and in Phane- 

 rogams (where heterospory is, of course, present) the gametophyte is 

 dioecious. In many of the Archegoniataa the gametophyte, however, is 

 hermaphrodite. It was observed that the prothallia of Osmunda were 

 hermaphrodite, and that they were capable of self -fertilisation. It must 

 be thus concluded that the reduction division in a hermaphrodite sporo- 

 phyte does not bring about a segregation of sex-characters. There is also 

 no doubt that the form of gametes produced from the gametophyte may 

 be influenced, within limits, during the independent existence of gameto- 

 phyte, by the environment. Also the form of gamete produced by any 

 gametophyte is independent of the sex-character transmitted through 

 that gametophyte to the sporophyte of the next generation. 



Replacement of Stamens by Carpels in Wallflower.! — C. Gcrber 

 has studied the anatomical structure of the supernumerary carpels which 

 replace the stamens in that cultivated form of the wallflower styled by 

 Be Candolle Cheiranthus Cheiri var. gynantherus. He finds that, whereas 

 a normal stamen receives only a single meristele from the central 

 cylinder, there is in addition in the staminal carpels a reversed bundle 

 such as characterises the false septum of the pistil. It is not therefore 

 correct to say that the stamens are transformed into carpels in this form 

 of the wallflower, but rather that the carpellised stamen differs from the 

 ordinary stamen by the addition to the vascular system of the latter of 

 the reversed vascular system characteristic of the pistil of Crucifers. 



Attraction of Colours and Scents for Insects.:}: — J. Perez, in a 

 second contribution to this subject, criticises the conclusions of Felix 

 Plateau on the same subject, and gives an account of his own observa- 

 tions on the visits of insects to flowers, and to other coloured objects. 

 He conceives the relation between insect and flower to be as follows. 

 Insects are guided to masses of flowers at a distance only by the scent 



* Proc. Camb. Phil. Soc, xii. (1904) pp. 430-40. 



t Comptes Rendus, exxxix. (1904) pp. 219-21. 



% Mem. Soc. Sci. Phys. et Nat. Bordeaux, se'r. 6, iii. (1903) pp. 1-30. 



