ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 189 



in anatomical connexion by association fibres. Within certain limits 

 there is no relation between the amount of cerebral material functioning 

 and the rate of formation of complex habits. In normal rats the habit 

 of brightness discrimination is mediated by the occipital pole of the 

 cerebrum (area striata), and by no other part of the cerebral cortex. 



J. A. T. 



Ear of Guinea-pig.— Geoeges Poetmanx (G. R. Soc. Biol., 1919, 

 82, 1384-6, 1 fig.). This differs from the ordinary mammalian type. 

 There is a median dumb-bell-shaped portion with a very narrow connect- 

 ing tube (the endolymphatic canal), two gradually expanding ends, one 

 of them intracranial (the endolymphatic sac, in close relations with the 

 lateral sinus), the other vestibular (the sacculus). From the sacculus a 

 very straight and short canalicule establishes communication with the 

 utriculus, and a larger one leads to the cochlear canal. In passing from 

 the sac to the saccule there is a gradual flattening of the epithelium 

 and a progressive development of perilymphatic spaces. The endo- 

 lymphatic sac is in intimate relations with the intracranial venous 

 system. J. A. T. 



Endolymphatic Sac and Duct in Do^. — Geoeges Poet^iann (C. R. 

 Soc. Biol, 1920, 83, 45-8, 1 fig.). The author's description of the 

 inner ear of the dog does not agree with what is believed to be usual in 

 mammals. The membranous internal ear shows a median dumb-bell-like 

 portion, with unequal expansions. The narrow median isthmus is the 

 endolymphatic canal. One gradually expanded end, the larger one, lies 

 intracranially, the endolymphatic sac, which is in intimate relations with 

 the lateral sinus. The other end, the smaller, is vestibular, and is the 

 sacculus. From the sacculus, and from about the same level, two 

 canaliculi arise, the upper one communicating with the utriculus, the 

 lower one with the cochlear canal. Emphasis is laid on the following 

 facts : — The endolymphatic sac is relatively very large ; its connexion 

 with the lateral sinus is intimate and extensive ; the epithelium is gradu- 

 ally flattened, and the perilymphatic spaces are increasingly developed in 

 passing from the sac towards the sacculus. J. A. T. 



Distribution of Parasitized Fish. — H. Chas. Willia^ison {Ann. 

 Applied Biol., 1919, 6, 48-52). What are called "spotted haddocks" 

 show in the muscles numerous cysts of a Protozoon parasite, Dokus cuius. 

 They have an unpleasant smell (suggestive of creosote), and are said to 

 have a sour taste. They seem to have a restricted geographical distri- 

 bution, about Shetland and west of Orkney, but the evidence is not very 

 convincing ; they are absent from Faroe. vSimilarly, " worm-infested 

 codlings," with numerous very-resistant Nematodes (like young stages of 

 Ascaris decipiens), coiled up in the muscles (able to survive brine-pickle 

 for half-an-hour and smoking for three-quarters of an hour or more), 

 do not occur at Shetland but at Faroe. It may be that local environ- 

 mental factors account for the diverse distribution of certain kinds of 

 parasitized fish. J. A. T. 



