390 SUMMABY OF CURRENT RESEARCHES RELATING TO 



of legs ; the moutli-organs have the form of a more or less bent rostrum. 

 At the extremity of the abdomen, on either side of the anus, there are two 

 semilunar retractile plates which serve either as organs of attachment or 

 to push the animal forwards. The sexual organs are unpaired, and their 

 apertures lie just behind the last pair of legs ; in the male the aperture 

 has the form of a fissure surrounded by swollen margins and with a sup- 

 porting plate ; in the female it is closed by a superior and an inferior 

 opercular plate. The rudiments of the sexual organs appear in the larvae 

 as solid cylindrical cell-bodies, and then proceed so far on the course of 

 their development that it is possible to distinguish the sexes before the 

 last month. Twenty-four species of gall-mites have as yet been closely 

 investigated. 



New Species of Mite.* — Herr G. Horvath found in barley certain mites 

 which occasioned an endemic skin disease among the workmen. Dr. Carpeles 

 describes and figures the larval and mature forms under the title Tarsonemus 

 intectiis. He believes that the form described by Flemming as T. uncinatus 

 belongs to the genus Pygmophorus. Skin eruptions of this kind have 

 hitherto been observed only in Hungary, with one exception.f Herr L. Orley 

 found larvae both in wheat and oats causing similar eruptions, and believes 

 that the Hungarian species probably has a much wider distribution. 



Development of Phalangida.J — Dr. H. Henking, in his investigations 

 into the developmental history of the Phalangida, has made use of a large 

 number of Opilio parietinus and of Leiohunum parietinum. With regard to 

 the ovarian ovum the author confirms the results of Blanc and Sabatier, 

 and has satisfied himself of the presence of a distinct yolk-nucleus in the 

 young ovarian ova ; the whole of it is often surrounded by a yolk-zone, and 

 is often constricted in the middle ; it disappears as soon as larger formed 

 yolk-masses appear in the egg. The young ovarian ova have the germinal 

 spot placed on a semilunar body consisting of granules that can be stained, 

 and which is of unknown function ; as in a number of allied forms, eggs of 

 moderate size have a distinct yolk-membrane. The ovum, when ready to 

 be laid, is, like that of insects, without any indications of germinal vesicle 

 or spot. The author is of opinion that there is no emission of semen at 

 the time when the ova are being laid, and he thinks that the structure of 

 the receptaculum seminis confirms this view. The mode of fertilization 

 and the causes of the disappearance of the germinal vesicle are discussed at 

 some length. When the ova are being laid a secretion is poured otit from 

 the glandular cells which invest the inner walls of the uterus and oviduct ; 

 this gradually hardens, and surrounds the egg as it were with a shell. 



Passing to the history of the development of the laid ovum, the appear- 

 ance of the first nuclei is described ; the earliest indications of these are 

 plasmatic networks of not inconsiderable size which arise separately from 

 one between the yolk-spheres ; treated wdth Flemming's chrom-osmium-acetic 

 acid, they are seen to be distinctly granulated. It seems, then, that in the 

 laid ovum of the Phalangida a number of new nuclei and cells appear by 

 free nuclear and cell-formation. The cells the author proj^oses to call pro- 

 tocytes, and the nucleus protokaryon, as Eay Lankester's name of auto- 

 plast has already been used by Krause with a different signification. 

 When treated with Flemming's fluid each of the networks is seen to become 

 slightly darker near its centre owing to the presence of a number of 



* Math. Term. Ertesito, iv. (1886). Cf. Centralbl. f. Bacteriol. u. Parasitenkuude, i. 

 (1887) p. 428. 



■j- Robin, C, Traite du Microscope, 1871. 



J Zeitschr. f. Wiss. Zool., xliv. (1886) pp. 86-175 (4 pis.). 



