ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 185 



them is very much less than it is, for example, in the Lepidoptera, and 

 their wings are therefore exceedingly light. 



The sixteen muscles and two ligaments are named and described, 

 and an account is given of the method adopted for securing instan- 

 taneous photographs of the insects' wings. Two phases are to be 

 distinguished in the movement of the wing, the movement from behind 

 forwards, and from in front backwards ; in both, however, there is 

 an upwardly acting force ; with this, there are associated other 

 movements, resulting in the course of the wing being a more or less 

 complicated curve, the directions of which depend of course on the 

 extent to which these other forces act. 



Nucleus of the Salivary Cells of the Larvae of CMronomus.* — 

 E. G. Balbiani reminds his readers that in 1876 he noted how the 

 epithelial cells of the ovary of the Orthopterous insect, Stenobothrus 

 pratorum, contained in their nuclei not ordinary nucleoli, but a large 

 number of small subequal granulations, which he compared to a mass 

 of bacteria. He showed that these united to form the filaments of 

 the nuclear figures which characterize the different stages of the 

 division of the nucleus (Karyokinesis), and that it followed that the 

 nuclear filaments were not, at first at any rate, homogeneous, but 

 formed of granules set along a single line. Confirmatory observations 

 have lately (1881) been made by W. Pfitzner on the Salamander ; but 

 instead of using his complicated method of demonstration, the author 

 has found that it is sufficient to treat fresh cells with acetic or chromic 

 acid : when the action is prolonged the globules may be seen to fuse 

 more or less completely with one another, and to give rise to filaments 

 which are sometimes varicose, and sometimes completely homocreneous • 

 it is under this condition that the nuclear filaments have generally 

 been described and figured. 



The salivary glands of CMronomus are two flattened organs, formed 

 of a small number of large clear cells, with large nuclei, transparent, 

 like the cells themselves ; in the nuclei there are two large nucleoli 

 formed by a granular refractive substance, and containing a more or 

 less large number of vacuoles. In addition to these, there is a pale 

 body of the form of a cylindrical cord, which is coiled upon itself in 

 an intestiniform fashion. In larvae of some age it is often broken up 

 into filaments of varying length which may either remain free, or 

 become attached to the envelope of the nucleus. Some little way 

 from each extremity the cord is suddenly swollen out, and this may 

 be described as a ring; when the cells are allowed to die in the 

 blood of the animal, the ring, which was previously difficult to detect 

 on account of its paleness, becomes finely granular, and so more 

 evident. In living cells it is perfectly homogeneous, being neither 

 granulated nor vacuolated. Entering into a detailed account of the 

 cord, the author describes its transverse strise and the disks of which 

 it seems to be composed. 



The influence of reagents reveals a difference in chemical com- 

 position; distilled water causes the cord to swell, till it becomes 



* Zool. Anzeig., iv. (1881) pp. 637-41 ; 662-66. 



