l888.] NEW-YORK MICROSCOPICAL SOCIETY. 31 



mouth and tongue, and also of the head itself, are produced by 

 these muscles. 



These striated muscle-fibres, when dissected out, as may be 

 seen in the other slide on exhibition, consist, as stated before, 

 of fibres that are streaked or striated across their length. They 

 seem to be more strongly and coarsely marked than the corres- 

 ponding muscles in man. A slide of human striated fibre is on 

 the table, and can be compared with that of the Harpalus, and 

 the difference will be noticed. 



The commonly-accepted theory has been that the striated 

 muscle-fibres of insects are not rounded at the ends, as they are 

 in the vertebrates. But you will notice in the slide under the 

 microscope, that a number of the round fibres have perfectly- 

 rounded ends. 



The contractile powers of the striated muscle-fibres in verte- 

 brates have been minutely and carefully studied and described 

 by many eminent histologists and biologists, of both this coun- 

 try and Europe. But little has been done in the way of study 

 or description of these movements in insects. There is a wide 

 field open for such investigations to any who may possess the 

 necessarily-required time and patience. It certainly would be 

 well worth the time spent to ascertain, if possible, by careful 

 dissections and microscopical examinations, whether the nerves 

 enter directly into the muscles, as in the vertebrates, and pro- 

 duce their excitation, and the consequent shortening in length, 

 by a direct so-called nervous-electric shock; or whether they 

 surround the muscle-fibres, and produce the result by a species 

 of induced, or secondary current. 



These striated muscle-fibres are of two kinds — flat and round. 

 I have not as yet been able to find the pyramidal fibres, men- 

 tioned by anatomists, in the head. These muscles are arranged 

 in layers. Newport and others call each layer a separate sys- 

 tem. But there is not as yet any definite opinion on that point, 

 and it can only be settled after long and patient study and 

 examination. 



The head muscles are stronger, less easily separated, and of a 

 whiter color than those in other parts of the insect body. And 

 I think it will be found that in the various carnivorous beetles, 

 and their larva, that the fibres are larger than in other beetles. 



In closing I would state that in dissecting insects, to reach 



