Miscellaneous. 491 



When the queen deposits an egg in a large cell intended for a 

 male, the edge of the cell exerts no pressure upon the abdomen, or 

 the pressure is exerted only above the seminal receptacle ; the latter 

 therefore is not raised, and the oblique position of the ejaculatory 

 canal in relation to the oviduct prevents the ejaculation. Thus, accord- 

 ing to the author, it is to the difference in the diameter of the cells 

 that the production of the different sexes in the Hive-Bee is due. — 

 Moleschotfs JJntersuchungen ; Bibl. Univ. de Geneve, September 

 1858, p. 94. 



On the Development and Propagation of the Trichocephalus dispar 

 mid Ascaris lumbricoides. By C. Davaine. 



1. The Trichocephalus dispar occurs so commonly in the caecum 

 of man, that the author calculates that in Paris one-half of the in- 

 habitants are infested by it. The development of this worm has not 

 been observed, and its mode of transmission is quite unknown. The 

 eggs are frequently evacuated with the faeces. The repeated examina- 

 tion of eggs found in the contents of the intestine of corpses, or in 

 the evacuations of patients, leads the author to conclude that these 

 ova undergo no development in the human intestine, and that they 

 are always expelled in the condition in v)hich they escape from the 

 body of the mother. The author therefore attempted to obtain the 

 development of the ova in water, but several times without success. 

 At the end of September, 18.37, he collected a great quantity of these 

 ova, and washed them for several days, until the water containing the 

 ova was limpid and destitute of any odour. The liquid was renewed 

 from time to time, and the ova were examined with the microscope 

 every week. A certain number underwent alteration ; others remained 

 uninjured, but without presenting any trace of development. At the 

 beginning of April, after six months' watching, the vitellus, in some 

 of these ova, collected into a rounded mass and acquired some con- 

 sistence, as was proved by crushing the ova. Some days afterwards, 

 the vitellus in many ova underwent segmentation into two, and then 

 into four parts ; the segmentation then followed the ordinary course, 

 and, at the beginning of May, many of the yelks had acquired a 

 mulberry-like appearance. From this time no change was observed 

 until the 12th of June, when some of the ova contained a well- 

 formed embryo, recognizable by its movements. This embryo, which 

 to a certain extent possesses the form of the adult, tapers gently 

 from behind forwards ; its length is about ^ niillim. 



2. On the 8th of October, 1857, the author collected numerous ova 

 o{ Ascaris lumbricoides by washing the fseces of a child who had passed 

 several of these worms. These ova were preserved in pure water, 

 and examined from time to time, like the preceding. For six months 

 no change was observed ; but on the 1 4th of April several of them 

 had undergone segmentation into two, and some into four parts, 

 whilst the greater number exhibited no change. On the 30th of 

 April, segmentation had taken place in all, but in various degrees : 

 in some the vitellus represented a small mannnillated sphere ; on the 

 5th of May this had become reniform, and on the 7th the embryo 



