622 EECOKD OF CURKENT RESEARCHES RELATING TO 



The larva resembles tliat of the common Scatophaga stercoraria L., 

 but is larger; it lives in the bladclerwrack between high and low- 

 water mark, the periodical wetting with sea-water being necessary, as 

 shown by experiments, to its existence. The pupte are found from 

 2 to 3 inches deep in the sand ; the imago emerges in from fourteen 

 to eighteen days. 



A hymenopterous parasite, resembling Smicra clavipes, was observed 

 to issue from the pupa in one case ; the egg must have been laid by 

 the female of that species, which is abundant, between the time that 

 the larva left the weed and that at which it entered the sand. The 

 parasite devours the entire interior of the pupa, and emerges in 

 eighteen days. 



Destruction of Noxious Insects by Mould.* — In answering Pro- 

 fessor Metschnikoff's remarks on Dr. Bail's discovery of the deadly 

 action of mould on insects, Dr. Hagen remarks that that observer 

 never applied his method to noxious insects, altliough he was suc- 

 cessful with other kinds. He himself has found that potato-beetles 

 took the disease thus engendered, and died in from eight to twelve 

 days ; the other half of the same lot of beetles, which were not 

 inoculated, lived through the winter in the same room. He has also 

 killed plant-lice in a hothouse by this means. He cannot agree with 

 Professor Metschnikoff that the discovery cannot be applied to prac- 

 tical r.ses until its scientific meaning is understood, for the results 

 already show that it is successful in practice, and its success is being 

 further tested by the experiments of many naturalists. 



y. Arachnida. 



Development of the Araneina.t — That Mr. Balfour's " notes " on 

 this subject were really wanted is shown by the extremely scanty list 

 of writers who have addressed themselves to the spiders, or to allied 

 forms ; tiie investigations now under consideration were made on 

 the ova of Agelena labyrinthica. The embryos were, after the method 

 of Bobretsky, hardened in bichromate of potash, after having been for 

 a short time in nearly boiling water. " They were stained as a 

 whole with hfematoxylin after the removal of the membranes, and 

 embedded for cutting in coagulated albumen." 



Segmentation of the Ovum. — When segmentation is complete, the 

 embryo is found to consist of a single layer of large flattened cells, ■ 

 with a central mass of yolk-segments, polygonal in form and made up of 

 a number of clear yolk-spherules ; among these yolk-segments we find 

 bodies which consist of a large nucleus, filled with aj^parent nucleoli, 

 and of a surrounding layer of protoplasm: each nucleated body 

 would seem to belong to a yolk-s])here, and to be placed at one side 

 of it ; the nuclei themselves would be derived from the nuclei of the 

 " segmentation rosettes." 



In the next stage, which is not far from that of the completed 

 segmentation, the ventral surface of the embryo is distinctly marked ; 

 it would appear to be made up of a procephalic lobe, an intermediate 



* ' Zool. Auzclg.,' iii. (18S0) p. 185. 



t ' Quart. Journ. Micr, Sci.,' xx. (1830) p. 1G7. 



