1888.] MICROSCOPICAL JOURNAL. 141 



lusks have been unfit to cut because of the hardness. I have observed this 

 caution in work on the cray-fish ovary and found no diflficulty in securing en- 

 tirely satisfactory sections, 



II. Gross anatomy. — The ovar}-. as before stated, lies chiefly in the trunk 

 or cephalothorax of the cra3--fish. It is seen in the freshly opened body, wdiere 

 none of the parts have been displaced, behind the stomach, almost hidden by 

 the liver on the sides and the -heart behind. The part thus seen is but a very 

 small portion of the entire organ, the remainder being concealed by the heart 

 and liver. If the heart be carefully removed the ovary can be seen to extend 

 backward beneath it, and removal of the muscles, which run from the front 

 abdominal segment above to the sides of the bronchial chamber, will demon- 

 strate the ovary extending back into the anterior abdominal segment. Careful 

 dissection with fine scissors and needles will permit one to separate the ovary 

 from the other organs about it. care being obsen-ed against mistaking the 

 oviduct for one of the bands of connective tissue. As the ovary is grad- 

 uallv disengaged it may be turned back, the oviducts cut oft', and the organ 

 received for further examination in a watch-glass of normal salt solution.* 

 Here its form and parts can be more carefully studied. It presents three por- 

 tions, two in front, a right and left half of equal size and similar shape, and 

 third single portion. The two front parts lie one on each side of the middle 

 of the bodv, and the single portion lies in the middle line of the body. In 

 the organ prepared without alcoholic hardening before a dissection the oviduct 

 cannot be easily distinguished, but in the alcohol-hardened specimen a string 

 of tissue will be found which passes from each of the two front portions of 

 the ovary down through the muscles of the ventral side, and which finally 

 run to the middle pair of legs. An examination of the under side of the 

 bodv will show that the basal joint of this middle pair of legs is enlarged, and 

 that a circular opening is placed on it looking backward. The opening is 

 covered with a membrane which acts as a sort of lip to close the opening. 

 The oviduct ends at this opening, and eggs which pass down the oviduct from 

 the ovarv escape through the opening to the outside, where they are caught 

 up bv the legs of the abdomen and fixed as ' spawn ' till the time of • hatch- 

 ing.' Naked eve examination of the ov^ary shows it to be made up of very 

 numerous small globular eggs, and demonstrates over these a very fine film, 

 which is recognized as covering the entire organ. A little teasing of the 

 ovary received in salt solution shows that this substance makes up the ovary, 

 and that the eggs are imbedded in it. It is in fact the ovary, properly speak- 

 ing, and the eggs, which are the conspicuous part of the organ, are the 

 products of its activity. 



III. Histology. 



I. Examination of the section. — The sections of the ovary, if no break 

 has distorted them, will show a number of similar large bodies made up of 

 many bright small droplets, some of them with a central body of large size, 

 and each one bounded bv a sharp line ; and, besides these largerbodies. numer- 

 ous smaller ones in the corners left among the larger ones. Figure i is de- 

 signed to show, in a semi-diagrammatic manner, the facts which any good 

 section illustrates. By name these different parts are (i) the &%Z-: (2) the wall 

 of the follicle, (3) the immature or young ^^"g. 



The egg. — Examination of the &^^ itself shows it to be a complex struct- 



* Normal salt solution is made by taking common table salt 6 parts to looo parts distilled water. It is used for 

 tissues to be examined fresh, instead of pure water, which is as fatal to fresh tissue^ as alcohol. It is better if 

 slightly warmed. The reason for its use is because it imitates the chemical character of fluids in the body. 

 Serum, or aqueous humor of the eye, or hydrocoele fluid, are still better. 



Instead of dissecting out the fresh ovary one can dissect under alcohol 50 per cent., and then receive the organ 

 in the same fluid. The latter process is easier, but it does not permit the examination of the contents of the 

 ovary in a fresh condition, which ought to be done. 



