100 M. O. Strobelt on the Anatomy and 



Anteriorly the penis, as well as the above-mentioned chitinous 

 bands, is in connexion with the united efferent duet of the 

 mucus-organs and seminal ducts. 



Muscular System and Movements. 



In the preparation of the muscles I have in general adopted 

 the method recommended by Landois as the most convenient. 

 He describes his process as follows (25, p. 499) : — " Select 

 individuals as large as possible, and lay them first of all for a 

 time in dilute alcohol, until a moderate hardening has taken 

 place. Then the individual is divided by a frontal incision, 

 by which the dorsal integument is separated from the ventral. 

 The two halves are now laid in water ; and when the viscera 

 have become sufficiently soft they are removed by means of 

 fine needles and hair-pencils. The integument*, with the 

 muscles, then remains. Staining brings out the picture." I 

 have divided the animals not only by frontal incisions, but 

 also by longitudinal sections into right and left halves, by 

 which means, besides the dorsal and ventral muscles in the 

 abdomen, previously unsuspected lateral muscles were exhi- 

 bited. Although certainly the preparation and investigation 

 of the musculature of such small animals is not one of the 

 easiest problems of anatomy, I believe that, from the great 

 number of preparations that I have made, I can give a tolerably 

 complete view of the musculature of Hcematopinus tenuirostris. 



The muscular bundles of the Arthropoda consist of the 

 sheath (sarcolemma) and the transversely striated contents, 

 the true contractile elements. In our animal 1 could only in 

 a few instances see the sarcolemma, but I could discover no 

 nuclei in it. The individual muscles break up into fibrillar, 

 the number of which varies according to the thickness of the 

 muscles. The finest presented only two fibrillse, while'stronger 

 ones had fourteen or more. In the fibrillar we see darker and 

 lighter layers alternate. These layers are sometimes perpen- 

 dicular to the long axis ; sometimes they form with it an 

 angle varying more or less from a right angle (fig. 5). The 

 interstices between the darker layers produce the transverse 

 striation. In Leydig's opinion (19) they are filled with semi- 

 fluid substance. At the extremities the fibrillar terminate 

 conically. By this means they are slightly separated from 

 each other, and thus the muscle appears to be fringed. All 

 the muscles are transversely striated. Only one, the flexor 

 tarsi\ has a sinewy termination (fig. 6,/h) The length and 

 thickness of the individual muscular fasciculi vary greatly : 

 thus, for example, in the abdomen their greatest length is 







