96 INVERTEBRATE ZOOLOGY. 



ted in an artificially injected specimen, and for this purpose a large form, like 

 the lobster, should be iTsed. With the alimentary canal occur various diges- 

 tive glands, one of which, the liver, is very constant in its occurrence. It is 

 to be expected below the stomach, and is generally brownish or greenish in 

 color and voluminous in size. Its connection with the alimentary canal should 

 be traced, after which it may be removed with a portion of the canal. The 

 stomach is peculiar in this animal and possesses a set of chitinous teeth, 

 worked by external muscles. This should be carefully examined. In a bi- 

 sexual form, as in this case, the sex should be determined by external indica- 

 tions if possible, and the internal reproductive organs should then be sought. 

 As essential parts of this, one may expect a germ gland, ovary or testis, and a 

 tube, generallj^ long, and often coiled, through which the germ cells may pass 

 to the exterior. In the male this tube is proportionally small, and is termed 

 vas deferens, while in the female it is often large, and termed oviduct. If a 

 portion of it is enlarged to serve as a receptacle for the retention of eggs or 

 embryoes, it is called the uterus. Accessory organs are common and may be 

 always expected, in the male, glands to secrete a liquid medium in which to 

 suspend the germ cells, and in the female, glands for yolk, shell-material, al- 

 bumen, etc., besides receptacles for spermatozoa, etc. 



Nephridia, either as separate tubes or united into a mass, may be expected 

 in any location, and in this case are in the form of the green gland, at the 

 base of the second Antennae. The nervous system is similar to those of the 

 earth-worm and grasshopper. The viuscidar system should be studied in con- 

 nection with the skeleton, whether external or internal. The mechanism of 

 a few joints, or of a few characteristic body-movements, will prove sufficient 

 in the general study of a type. 



68. Histological study. To obtain and preserve material for the study of 

 cell structure, an animal should be killed by chloroform, and dissected either 

 in the air or under water. The parts to be sectioned should be selected, cut out 

 as rapidly as possible, and preserved by the method recommended for pieces of 

 earth-worms, 61 b, I and II. The pieces selected should be small, and sepa- 

 rated as much as possible to allow the ready access of the reagents to all 

 parts. After preservation, the parts may be kept in small bottles of 70 % well 

 labelled. For sectioning, a piece may be stained in toto, the principal being 

 the same as in the staining of hydroids, the amount of time being regulated 

 by the size and density of the piece. From the turpentine the piece is put 

 into melted paraffine (in the parafifine oven) and imbedded when completely 

 infiltrated, It is impossible to assign exact times for the different procedures, 



