OBSERVATIONS ON STRIPED AND UNSTRIPED MUSCLE. 89 



Arthropoda. 



Representatives of the Crustacea and Insecta, viz. the Lob- 

 ster, Dysticus, and the Bee, were investigated by Mr. Melland, 1 

 the network (of striped muscle) being found in each case. 



Astacus, Heart-muscle. — Gold preparations of the heart 

 of the Crayfish show the network to be present in this muscle 

 as in the body muscles ; the network is, however, much finer 

 and more difficult to demonstrate (fig. 6). 



The muscle-fibres of the heart are intimately blended with 

 what appear to be large masses of granular protoplasm enclos- 

 ing nerve-cells ; these may possibly be of the nature of nerve- 

 endings. 



Daphnia. — As a representative of the minuter forms of 

 Crustacea, I examined the Daphnia. The muscle-fibres of this 

 animal, when examined in the fresh state, only show transverse 

 striation faintly. After many attempts I succeeded in obtaining 

 a satisfactory gold preparation, where the muscle-fibres were 

 much softened and pressed out to many times their normal 

 diameter. These fibres show the network very plainly (fig. 7). 



In this case the animal was placed whole in 1 per cent, acetic 

 acid for ten minutes, and left in the formic acid in a warm 

 chamber at 40° C. for two hours. 



Insect Larva. — To determine if striped muscle is present 

 in the larval insect as well as in the imago, I made prepara- 

 tions from the larva of the Ermine Moth (Spilosoma lubri- 

 cepeda). Muscle was taken both from the jaws and from 

 the legs. In both cases the muscle was found to be striped, 

 the network in the muscle of the jaw being especially well 

 developed. 



Arachnida. 



Muscle taken from the leg of the Spider and treated with 

 gold showed the network of striped muscle. 



1 Loc. cit. 



