Miscellaneous, 353 



to distinguish a double contour in them ; they are lenticular, pretty 

 strongly coloured red by carmine, and present in their interior some 

 darker granules. From the first day of pupal life the primitive 

 bundles thus constituted begin to disappear, and this according to 

 two different modes, both of which may be observed in the same 

 animal. One of these modes is characterized by the excessive 

 activity and proliferation of the muscular nuclei ; the other, on the 

 contrary, by their degeuerescence and death. 



1. Disappearance of the Muscle accompanied hy Proliferation of the 

 Nuclei. — In the bundles which disappear in accordance with this 

 mode, the sarcolemma has disappeared even before the envelope of 

 the pupa has acquired its characteristic brown appearance ; the con- 

 tractile substance has become homogeneous ; the nuclei, both those 

 situated beneath the sarcolemma and those in the midst of the con- 

 tractile mass, have become spherical, and acquired the property of 

 being coloured by carmine of a very dark purplish red, which cha- 

 racterizes them. Such a nucleus soon acquires the value of a 

 complete cell ; it is surrounded by a layer of protoplasip, which is 

 itself clothed with an enveloping membrane. In this protoplasm 

 are seen four or five spherical granules of a bright rose-colour ; 

 these granules enlarge, and soon attain the size of the nucleus, when 

 there is produced a mulberry-like mass composed of five or six 

 grains lodged in a common envelope. One of these grains, the true 

 muscular nucleus, is of a purple-red, while the others are bright 

 rose-colour. The membrane soon disappears, and the purple and 

 rose-coloured nuclei separate. 



This proliferation of the muscular nucleus takes place on the spot ; 

 and the contractile substance becomes absorbed around it to lodge 

 these new formations. These light rose-coloured nuclei, the mode 

 of formation of which we have just seen, multiply in their turn by 

 a mode analogous to that which gave them birth. In proportion as 

 the embrj'onic cells thus produced increase in number the contrac- 

 tile substance is absorbed. In a section the primitive bundle then 

 appears constituted as follows: — The contractile substance, which 

 has become perfectly homogeneous, exhibits a deeply notched sinu- 

 ous border ; these sinuosities are occupied by the embryonic cells, 

 due to the proliferation of the muscular nuclei ; and they are deeper 

 in proportion as this accumulation of embryonic cells is more con- 

 siderable. The central part of the contractile mass appears pierced 

 with holes of irregular outline, filled with embryonic cells due to 

 the proliferation of the intramuscular nuclei. 



At a more advanced stage the place that was occupied by the 

 musciilar bundle is indicated only by a mass of embryonic cells in 

 course of incessant proliferation. 



2. Disappearance of the Muscle accompanied hy the Degenerescence 

 and Death of its Nuclei. — After the disappearance of the sarcolemma 

 the muscular nuclei appear with a very distinct envelope presenting 

 a double contour ; they still retain their lenticular form ; their 

 centre is occupied by a small spherule formed of fine granules, which 

 are then the only coloured parts of the nucleus. The granules 



Arm. & Mag. N. Hist. Ser. 5. Vol vii. 26 



