BIOLOGY. 277 



marsupial and monotreme animals examined (sufficient to enable 

 us to affirm without much hesitation that tlie character is univer- 

 sal), it lies abov'e them, as distinctly seen in the transverse sections. 

 This is precisely the same relationship wliich obtains in man and 

 all other mammalia, and this is one of the chief points in which 

 not only the interpretation of facts, but the observation of them 

 recorded in the present paper, differs from that of Prof. Owen. 



The defective proportions of the part representing: the great 

 transverse commissure of the placental mammals, whicli ajopear 

 to result from or to be related to the peculiar confirmation of the 

 wall of the hemisphere, must not lead to the inference tliat the 

 gi-eat medullary masses of the two halves of the cerebrum are by 

 any means "disconnected." The want of the upper fibres is 

 compensated for in a remarkable manner by the immense size of 

 the anterior commissure, tlie fibres of whicli are seen i-adiating 

 into all parts of the interior of the hemisphere. There can be 

 little doubt that the development of this commissure is, in a cer- 

 tain measure, complementary to that of the corj^us callosum. 

 This is, moreover, a special characteristic of the lowest group of 

 the mammalia, most remarkable because it is entirely lost in the 

 next step of descent in the vertebrated classes. 



After a description of the brain of a bird, the conclusion is 

 arrived at, that, great as is the difference between the placental 

 and implacental mammal, in tlie nature and extent of the connec- 

 tion between the two lateral liemisj^heres of the cerebrum, it is 

 not to be compared with that which obtains between the latter 

 and the oviparous vertebrate. 



SOURCES OF THE FAT OF THE ANIMAL BODY, BY J. B. LA WES 

 AND DK. J. H. GILBERT. 



In 1842, Ba,ron Liebig had concluded that the fat of Herbivora 

 must be derived in great part from carbo-hydrates of their food, 

 but might also be produced from nitrogenous compounds. Du- 

 mas and Boussingault had at first opposed this view ; but subse- 

 quently the experiments of Dumas and Milne-Edwards with bees, 

 of Persoy with geese, of Boussingault with pigs and ducks, and 

 of the authors with pigs, had been held to be quite confirmatory 

 of Liebig's view, at any rate, as far as the carbo-hydrates were 

 concerned. But at the Bath meeting of the British Association, 

 in 18G4, Dr. Haydon expressed doubt on the j^oint ; and at the 

 Congress of Agricultural Chemists, held at Munich last year. 

 Prof. Voit, from the results of experiments with dogs fed on 

 flesh, maintained that fat must have been produced from the nitro- 

 genous constituents of the food, and that these were probably 

 the chief, if not the only, source of the fat of the Herbivora. 

 Baron Liebig disputed this conclusion; and his son, Hermann V. 

 Liebig, has since sought to show its fallacy by reference to cows. 

 The authors agreed with the conclusions of these latter authorities, 

 but pointed out the inadequacy of the data relied upon by Her- 

 mann V. Liebig. They showed that, owing to the much less 

 proportion of alimentary organs and contents, the higher charac- 

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