MOULTING HABITS OF SPIDERS. KM 



Waldemar Wagner, the Russian savant, whose skillful and patient researches 

 have heretofore been quoted. I shall draw chiefly upon his work " La 

 Mue des Araignees " for the material which it serves me to pre- 

 Physio- sen ^ here. For full information the student is referred to Mr. 

 ogica \Y a g n er's paper. It will sufficiently answer the purpose to give 

 Changes. a g enera -l notice of the development of the process, and to illus- 

 trate these by quoting somewhat in detail, in the case of several 

 organs, the genesis of the new skin and the rejection of the old. 



Ordinarily the matrix of spiders presents a layer of protoplasm with 

 numberless cells. This is colored equally throughout, the cell, as usual, 

 being more, the plasma less, intensely colored. As the moulting time 

 approaches one ceases to observe this equality of coloration ; the superior 

 layers next the old cuticle are colored more and more feebly ; and finally, 

 at the moment when the contingent layer ceases to be colored and loses 

 its granulation, and when, consequently, we may rightly consider it as trans- 

 formed into a chitinogenous layer, then the future tegument begins slowly 

 to separate from the old. 



As the new skin is retracted from the old cuticle the interval thus 



formed is filled with liquid, in small quantity at first, but gradually 



increased with the enlargement of o . 



' the cavity. The new tegument fJi- 



New Skin. J -.-;-. ., :?T^V^-*V-^-^ 



increases rapidly; within the ceph- jffo ..-iT'j^-">l*-if.".^ '" y ^ ^ 



alothorax, not being able to have full exten- i^.-~. :.:' v &' ' 



Sion, it forms many folds (Fig. 67, f.n.t), F '- f-n.t, folds of new tegument ; Mt, 



' ' matrix ; section showing folds of new 



destroying thereby the layer of the old tegument under the old (o.t). 

 cuticle, which is drawn from it, and from which it is disengaged little by 

 little. On the abdomen one does not observe these foldings of the new 

 skin, because the old is there so pliable that it does not impede the growth 

 of the new. At the moment when the new hairs are completely formed 

 there remain of the old skin, separated from the new, only the tubes which 

 serve as sheaths for the new hairs ; and, on the day of the moult or the 

 day before, these sheaths are destroyed, and the liquid underneath the 

 tegument disappears. 



The moult of the eyes takes place simultaneously with the other organs ; 

 the matrix in process of growth insinuates itself between the vitreous body 

 and the preretinal envelope, the cells of which are in that way 

 forced upward and lose their regular form. The moulting of all 

 the eight eyes does not take place at once, but probably at differ- 

 ent times. With Attus terrebratus, at least, the lateral eyes are the first to 

 end their moult. For a period longer or shorter before the rejection of the 

 old skin, according to the stage of development, spiders lose their sight, 

 and after the moult vision is not restored all at once. 



During the moulting of the lungs breathing is difficult, but the time 

 occupied therein is short. Two of the three layers which compose the 



