40 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the former of which lie near the lumen and the latter near the wall 

 of the gland. Between the separate follicles we find a connective 

 tissue with the characters of fat-cells and traversed by renal cauali- 

 culi. The secretion of the gland is neutral or faintly acid ; on being 

 dried and heated with fibrin it gave its distinct peptine reaction, which 

 was most marked in alkaline solutions ; it appears to possess both a 

 tryptic and a peptic ferment. 



Limulus an Arachnid.* — Professor E. Eay Laukester examines 

 part for part the apparently corresponding structures of Limulus (the 

 King-crab) and a Scorpion. Commencing with the nervous system, an 

 exact knowledge of which in the latter is still a desideratum, he points 

 out that in Limulus we have (a) an archi-cerebrum whence five nerves 

 only are given off ; (6) an oesophageal collar whence nerves radiate to 

 all the pediform gnathites, as well as to the chilaria and the genital 

 operculum, there being a distinct nerve for each appendage ; (c) the 

 first half of the abdominal cord gives off no nerves, the latter five pairs. 

 Precisely corresponding portions may be made out in Scorpio, where, 

 however, the brain and the oesophageal collar are more intimately 

 fused ; Newport's figure shows that the nerves "have a lateral position 

 embracing the true archi-cerebrum." What Professor Lankester calls 

 the attraction of nerve-organs to the oesophageal collar has gone further 

 in Scorpio than in Limulus, for the nerves for the segments contain- 

 ing the first two pairs of lung-books likewise arise from the collar 

 itself. 



The striking resemblances between the skeletons of the two forms 

 are next illustrated, and it is pointed out that the so-called compound 

 eyes of Limulus are more correctly regarded as aggregations of simple 

 eyes; the differences between the abdominal regions are diminished 

 when we remember that the embryonic Limulus has a series of separate 

 segments in this region, the presence of which is still denoted by a 

 series of ridges and by the lateral spines, each of which would appear 

 to possess its separate musculature, as well as by the dorsal pits or 

 " entapophyses." Between this and the anus, Limulus has an area 

 which is only potentially segmental, and behind these comes in both 

 a telsonic spine. Behind the six cephalo thoracic appendages there is 

 the genital operculum, a lid-like plate which in Limulus retains 

 throughout life indications of its double origin, but in Scorpio is only 

 bifid at its free margin. As is well known, the 8 th pair of the 

 appendages in the Scorpion are the pectines ; in the King-crab, the 

 pieces on either side become united across the middle line, but on 

 their under surface there is still to be seen " a series of very delicate 

 lamellae, corresponding to the lamelliform teeth of the Scorpion's 

 comb-like appendages. Precisely similar pieces are found on the 

 9th-12th appendages of Limulus, but in the Scorpion the rudimentary 

 appendages have disappeared," but only from view — in other words, 

 the lamelligerous appendages of these four segments sink within the 

 lung-invaginations. When a close examination of the sternal area of 

 this region of Limulus is made stigmata are found which lead into 



* Quart. Journ. Micr. Sci., xii. (18SI) pp. 504-48 (2 pis.). 



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