The Lobster. 87 



specimen is a female the essential reproductive organs are 

 the ovaries. Their position, color, and relation to the other 

 viscera, should be clearly determined. How are they held 

 in place? Can water be injected into them through the 

 openings at the bases of the ambulatory appendages? 

 Examine the oviduct and note its course. Are the eggs in 

 different portions of the organ of about the same size ? 



Make a longitudinal incision through the ovarian wall 

 and examine the interior. How are the eggs held in place ? 

 Is the wall of the oviduct in any way different from the 

 same of the ovary? It is probable that it secretes a cover- 

 ing for the eggs, as they are being extruded, which attaches 

 them to the hairs of the abdominal appendages. 



Open the receptive apparatus and place some of the con- 

 tained fluid on a microscope slide. Do you find, on exam- 

 ining the preparation with a high power, that spermatozoa 

 are present? If the specimen which is being dissected 

 measures ten inches in length, it will in all probability con- 

 tain many of these male-cells, the structure of which is given 

 below. 



Draw the ovary. 



Examine a male specimen. Note the position, color, and 

 extent of the tesfes, the essential reproductive organs of the 

 male. In what respect do they differ from the correlative 

 structures of the female? Endeavor to inject through the 

 external openings. Is the course taken by the rasa defer- 

 entia in any way different from that taken by the oviducts? 

 Do you find the median portion of the vasa deferentia 

 enlarged? Can you induce the extrusion of the contents 

 (spermatophore) of this enlarged portion? Slit open one of 

 the testes and place some of the contained fluid on a slide. 

 Cover, and examine as above directed. 



