THE AMERICAN LOBSTER. 14!) 



VARIATIONS IN OTHER ORGANS. 

 ROSTRUM. 



I have met with a single ease of bifurcated rostrum, a small male, represented 

 iu figs. 102, 163. The median groove, which corresponds to an area of absorption in 

 the shell (see p. 88), divides near the apex, each branch going to a terminal spine. 

 Instead of a single spine below the terminal, there are several smaller ones. 



In AVpheus saulcyi the median rostral spine is sometimes wanting, as in the genus 

 Betaeus, of Dana. (See 94, p. 384, plate xxh, fig. 11.) 



OVARY. 



Two instances were observed in which the ovarian lobe on one side has suffered 

 division, one that of a small female (44 mm. long, fig. 131, plate 38) in which one 

 of the posterior lobes is involved, the other an adult lobster (fig. 164, plate 42) with 

 similar division of the left anterior lobe. 



HERMAPHRODITISM. 



A malformed hermaphrodite lobster, Homarus gammarus, was described and fig- 

 ured by Nicholls in the Philosophical Transactions of the Loyal Society of London 

 in 1730 {141). " The specimen," he says, " if split from head to tail, is female on the 

 right side and male on the left side." This was true of both the internal and external 

 organs. A similar case of hermaphroditism has been described by Gissler (78) in the 

 Phyllopod Etibranchipns vernalis. 



La Valette St. George (193) discusses a very interesting case of hermaphroditism 

 which he discovered in the crayfish. He found eggs present in the nearly ripe testis 

 of Astacus fluviatilis in July and August. The eggs were placed usually at the 

 periphery of the testis lobe. They were round or oval, 0.00 mm. to 0.015 mm. in diam- 

 eter, and showed the usual constituents of ovarian eggs. They had a larger germinal 

 vesicle than the normal egg, were sometimes inclosed in a follicle, and contained yolk 

 spheres. He asks how the presence of the eggs in the normal testicle is to be explained 

 and gives the following answer: 



These eggs are evidently derived from spermatogonia, which have become unfaithful to their 

 original functions. Instead of multiplying by division to form a number of spermatocytes, they have 

 chosen a shorter way, which makes it possible for a single egg to arise from them by simple growth. 



Under certain conditions a primitive sperm cell may be converted into an egg 

 cell, and this, he says, furnishes a new proof of the relation of spermatogonia and 

 oogouia. Follicle cells may arise from a spermatogonium, but the latter can never 

 arise from follicle cells. 



The spermatogonia, according to La Valette St. George, produce, chiefly by mitosis, 

 the spermatocytes, which eventually give rise to the spermatids. Spermatosomes, as 

 well as large follicular nuclei, may be found in the process of degeneration iu the testis. 



Hermaphroditism has also been described in the lobster by Hermann (89), who, 

 according to La Valette St. George, was the first to prove the presence of hermaphro- 

 ditism in the testes of decapods. Hermann discovered in the anterior parts of the 

 testis of the lobster large round or oval cells with granular protoplasm, each pos- 

 sessing a large germinal vesicle with nucleoli. Eight or ten such cells, which were 

 regarded as undoubted eggs, were found in one specimen. In some of the figures 

 given by La Valette St. George the ovum fills nearly the entire lumen of the testis. 



