February 14, ]913] 



SCIENCE 



267 



A. M. Reese (West Virginia University) : The 



Histology of the Enteron of the Alligator while 



Bibernatiiig and while Feeding. 



The chief object of this investigation was to 

 determine the effect of hibernation upon the di- 

 gestive tract of the alligator, and incidentally to 

 study the histology of these structures, which has 

 not, so far as the author is aware, been done 

 before in any detail. 



The material used was taken from young ani- 

 mals at the end of a feeding period of about five 

 months, and towards the end of the hibernating 

 period after fasting for four or five months. 



The regions of the enteron that were studied 

 were as follows: the tip and base of the tongue; 

 the anterior and posterior regions of the roof of 

 the mouth; the anterior and posterior regions of 

 the esophagus; the cardiac, fundic and pyloric 

 regions of the stomach; the anterior, middle and 

 posterior regions of the small intestine; the an- 

 terior and posterior regions of the rectum. 



Since the work was started at the end of the 

 hibernating period the tissues of that period were 

 studied and drawn first. 



The only difference between the structure of 

 the tip of the tongue during hibernation and 

 during the feeding season is that the scaly epi- 

 thelium with which it is covered is somewhat 

 thicker and more compact in the former than in 

 the latter condition, though even this difference 

 may have been due to differences in the ages of 

 the animals used. The base of the tongue differs 

 from the tip in having a thicker epithelium and 

 in having compound, tubulo-alveolar glands. 

 These glands in the hibernating animal have many 

 more alveoli than in the feeding animal, though 

 this, again, may have been due to the difference 

 in age. 



The lining of the roof of the mouth is essentially 

 the same as that of the tongue. The glands are 

 found only in the posterior region. The slight 

 differences in the papilla here found may easily 

 be due to the difference in age. 



The esophagus shows the usual layers for that 

 region. Its epithelium is partly ciliated in the 

 anterior part. The muscularis mucosa is very 

 scant in the anterior region. The only difference 

 between the two stages is that in the feeding the 

 muscularis mucosa in the anterior region is much 

 more strongly developed than in the hibernating 

 stage; and in the former the nuclei are not ar- 

 ranged in two zones as in the latter. 



The stomach has the usual layers, and has 

 essentially the same structure in the three regions 

 studied, except that the wall in the fundio region 

 is much the thickest, due mainly to the great 

 thickness of the middle muscular layer. Only one 

 kind of cell is found in the gastric glands. No 

 difference is to be noted between the hibernating 

 and the feeding conditions. 



The chief peculiarity of the small intestine is 

 the apparent entire absence of the submucosa. 

 Goblet cells are also wanting. The greater diam- 

 eter of the anterior region is due both to the 

 greater diameter of the lumen and to the greater 

 thickness of the walls. The middle and posterior 

 regions have about the same diameter, though the 

 mucosa becomes thinner and less complicated 

 caudad. There is practically no difference be- 

 tween the hibernating and feeding stages. 



The anterior and posterior regions of the rec- 

 tum have essentially the same structure. No dif- 

 ference can be seen between the hibernating and 

 feeding conditions. 



The differences, then, between the digestive 

 tracts of the hibernating and feeding animals are 

 so slight that it may be said that hibernation has 

 practically no effect upon the enteron of the alli- 

 gator, at least in captivity, 

 r. W. Caepentee (University of Illinois) : 



Methylene Blue Preparations of Nerve Endings 



in Cranial Autonomic Ganglia. (Demonstra- 

 tion.) 

 H. L. Bruxee (Butler College) : Jaooison's Organ 



and the Bespiratory Mechanism of the Urodeles. 



In the amphibians the relation between respira- 

 tion and smell is complicated by the peculiar 

 nature of the respiratory mechanism, which in- 

 cludes an apparatus for closing the nasal passage. 

 In this group Jacobson's organ, when present, is a 

 blind sack or groove opening into the general ol- 

 factory cavity. According to the theory of Seydel 

 (1895) it is stimulated by odorous material which 

 passes through the choana from the mouth. The 

 organ in question has been recognized in the 

 Amira and Salamandrida and among the lower 

 urodeles, in Cryptoiranchus and Amphvama. It is 

 wanting in Froteus and Neoturus. 



Among the amphibians studied, the organ of 

 Jacobson is present in all forms in which the 

 expiratory media pass through the nose in adult 

 life. In Necturus and Proteus access to the nasal 

 cavity from the mouth is prevented by a mechan- 

 ical breathing valve at the choana and the organ 



