April 3, 1903.] 



SCIENCE. 



537 



by the Canadian pathologist, Chas. H. Hig- 

 gins.* 



A New Method of Embedding Small Ob- 

 jects: George Lbeevke, University of 

 Missouri. 



A special form of watch-glass was de- 

 scribed which obviates the usual difficulties 

 encountered in embedding loose, minute 

 objects like eehinoderm eggs. 



The dish is a flat, solid watch-glass, con- 

 taining a shallow concavity, in the bottom 

 of which is molded a narrow, slot-like 

 groove or trough. 



The objects, after saturation with the 

 solvent, are transferred to the dish, filled 

 with melted paraffin and kept warm on 

 the bath, by carefully dropping them from 

 a pipette into the groove, where, owing to 

 the confined space, they will remain closely 

 massed. The bottom of the dish is then 

 rapidly cooled on the surface of water, and 

 the paraffin, when thoroughly hardened, 

 may be removed without difficulty. The 

 objects are held in the portion of the par- 

 affin which previously filled the groove and 

 which now projects from the surface of 

 the block. The block is then attached to 

 the paraffin-holder of the microtome, and 

 the objects are ready for sectioning. 



The practical usefulness of this dish has 

 been thoroughly tested, and experience has 

 shown that it may be manipulated so easily 

 and conveniently that the embedding in it 

 of such minute objects as it is intended 

 for becomes as simple an operation as the 

 embedding of larger ones which may be 

 handled individually. 



In addition to its use as described above, 

 the dish is serviceable for the purpose of 

 orientation. A small object lying in the 

 groove may be rapidly oriented with a 

 warm needle under the microscope and 

 placed in any desired position. It is then 

 possible to cool the paraffin without dis- 

 turbing the object. 



* Acetylene Gas Journal, 1901. 



The Heredity of Sex: W. E. Castle, Har- 

 vard University. Presented by title. 

 (Published in full in Bulletin Mus. 

 Comp. Zool., Harvard College.) 



1. Sex is an attribute of every egg and 

 spermatozoon. It is independent of en- 

 vironment, and is inherited in accordance 

 either with Mendel's law of heredity or 

 with the principle of mosaic inheritance. 



2. Mendel's law includes (a) the prin- 

 ciple of dominance in the zygote of one of 

 two alternative characters over the other, 

 and (&) the principle of segregation of 

 those characters at the formation of 

 gametes. 



3. In mosaic individuals alternative char- 

 acters coexist without dominance of either ; 

 they pass together {without segregation) 

 into the gametes. 



4. Mendel's law governs the heredity of 

 sex among difficious animals and plants; 

 but hermaphroditic organisms are sex- 

 mosaics, and form only mosaic gametes. 



5. In dioecious organisms, (a) one sex 

 dominates, the other is latent; (&) each 

 gamete bears the characters of one sex 

 only, but can unite in fertilization only 

 with a gamete bearing the characters of 

 the opposite sex; (c) in the zygote some- 

 times the male character dominates, some- 

 times the female. 



6. In partheno genetic animals the female 

 character invariably dominates over the 

 male when both are present together. In 

 such animals, {a) all fertilized eggs are 

 female; (b) unfertilized eggs produced 

 without segregation of sex-characters are 

 female; (c) males develop only from un- 

 fertilized eggs from which the female 

 character has been eliminated. 



7. The female character eliminated from 

 the male parthenogenetic egg passes into 

 the testis; hence the spermatozoa of par- 

 thenogenetic animals are female (example, 

 honey-bee). 



