PHYSIOLOGY. 



653 



rate> of osmosis df sul stances bear constant i 

 to their final osmotic pressures, and whether the 

 ;ice of proteid substances in tlie solutions 

 affects the initial rate of osmosis. The author has 

 found that the initial rates of osmosis can not be 

 determined from observations of the freezing pow- 

 ; solutions, and that proteid substances, even 

 when present only in minute quantities, diminish 

 the rate of osmosis to a marked degree. Dr. Bar- 

 low further applies these conclusions to the con- 

 sideration of lymph formation, and describes ob- 

 servations of the specific gravity of the blood, of 

 voluntary muscle, and of lymph, which have an 

 important bearing on the question. In his conclu- 

 sion he summarizes the evidence in favor of the 

 occurrence of osmosis and increased infiltration as 

 the effective factors in causing the increased out- 

 flow of lymph that is seen alter the injection of a 

 crystalloid into the blood, as well as the evidence 

 against the view that osmosis and increased filtra- 

 tion alone account for the observed phenomena. 



A study of rowing has been applied by Dr. F. 

 Ahlhorn to explain the use and meaning of the 

 asymmetrical types of tail fin often met with 

 among fishes, such as the upturned tail of the 

 shark and sturgeon and the downwardly extended 

 tail of the flying fish. All rowers are acquainted 

 with the results of holding their oars too obliquely 

 in the water. If the upper edge is turned too much 

 toward the stem of the boat, a brisk pull brings the 

 blade out of the water and the oarsman is thrown 

 backward from his seat : but if the blade is inclined 

 in the opposite direction, it digs into the water and 

 the oarsman "catches a crab.'' The skeletal sup- 

 port of the asymmetrical fins of fishes is generally 

 such that either the upper or the lower border of 

 the fin offers more resistance to the pressure of the 

 water than the opposite border, whereby the fin is 

 caused to assume an oblique instead of a vertical 

 position. Then, where the upper part of the tail is 

 stiffer than the lower as in the heterocercal tail of 

 the shark and sturgeon the tail in locomotion is 

 driven upward: while if the lower part of the tail 

 is firmer than the upper as in the flying fish the 

 tail tends, in action, to assume a lower position than 

 the rest of the body. The body of the animal, in 

 fact, is made to swing vertically about a horizontal 

 axis running through the center of gravity." In 

 the first group the tail becomes elevated above the 

 head, and the bottom-haunting fish composing it 

 are enabled to give free play to their tails while 

 scouring the sea bottom in search of food. In the 

 second group the head becomes raised above the 

 tail. It consists of surface-swimming forms, which 

 are thus enabled, by the adaptation of their struc- 

 ture, to swim swiftly beneath the surface of the 

 water without danger of their tails emerging, and 

 so causing inconvenience and waste of force. The 

 tails of many air-breathing aquatic animals, such as 

 the crocodile, water snake, and the extinct icthyo- 

 saurus. are constructed on this principle. 



In his examination of the opposition of the thumb 

 Dr. Rene du Bois-Reymond studied in detail the 

 theory of saddle joints', and on the assumption that 

 the movements take place about two axes at right 

 angles to each other and passing through the point 

 of contact of the two bones, he arrived by construc- 

 tion at a mathematical formula corresponding to 

 the ideal saddle joint. The formula shows that a 

 certain amount of rotation is possible in this joint. 

 The author further investigated, by the horopter 

 and photographically, the actual movements of the 

 thumb, the hand being fixed. 



In a paper on the formation and structure of 

 dental enamel Dr. J. Leon Williams disc; 

 1. The existence of a very thin membrane, or a 

 structure of inernbranelike appearance, lying be- 



tween the ameloblasts and the forming enamel, and 

 also between these cells and th"- 

 ti-rinu/iii/it. A similar membrane was seen in many 

 ing the odnntoblaMs. '-'. Tin- for- 

 mation uf enamel by dcpu.-it. and not by cell calci- 

 fication. This deposit probably CHHM>;.- of two dis- 

 tinct cell products a granular plasm and splx : 

 of calcoglobulin. 3. The relation of the cells of the 

 stratum inftrnifdium to true secreting tissue, the 

 relation being especially marked in the enamel or- 

 gans of the rat and mouse. 4. An intricate vascu- 

 lar network in the stratum ititi.rmi-dium. A free 

 distribution of blood vessels was ol served in the 

 chloroblastic layer of cells in the mouse, rat, and 

 calf, as well as in the human embryo. 5. The 

 fibrous character of enamel in many of the lower 

 animals and the change of the fibers into more or 

 less regularly arranged granules in the monkey and 

 man. 6. The author affirms that the varicosities of 

 the enamel rods are not caused by acids (though 

 often rendered more clear to view by acid treat- 

 ment), but represent a true structural peculiarity of 

 this tissue: and that these varicosities. which often 

 continue in an uninterrupted line across large fields 

 of view, correspond with the course of one set of 

 fibers. 7. The Retzius bands are often as distinctly 

 marked in forming as in mature teeth and in teeth 

 which have been kept constantly moist as they are 

 in dried specimens. The enamel rods are often seen 

 to pass without break across several of these bands. 

 The bands are principally due to a deposit of pig- 

 ment, ami not to imprisoned air or gas, as is claimed 

 by von Ebner. 



In view of the great discrepancies in the pub- 

 lished results of the analysis of enamel Charles S. 

 Tomes endeavored to estimate the organic matter 

 directly, and was surprised to find that it did not 

 exist in weighable quantity. Other results of his 

 studies of the composition and nature of this sub- 

 stance are that there is at least one equivalent of 

 water in combination with the calcic phosphate, 

 and this, unmentioned in the analysis, has gener- 

 ally figured as organic matter. Further, that there 

 is more water than this in the enamel: "it may be 

 that from its physical structure it is very hard to 

 dry. though longer drying and a somewhat higher 

 temperature make little difference to it ; or it may 

 be that there are two equivalents in composition, and 

 that the salt is exceedingly hard to decompose abso- 

 lutely at the temperatures obtained. The enamel 

 of the elephant's molar (on which the experiments 

 were mostly made) must then be considered as an 

 almost inorganic crystalline structure, and, so far 

 as my investigations have gone, there is no reason 

 to suppose that the enamel of man, the horse, and 

 the ox. differ materially from it." 



In his investigations of the physiological influence 

 of alcohol, C. F. Hodge has regarded the influence 

 upon growth, including reproduction, upon psychic 

 development and upon animal activity and ability. 

 With fresh cultures of yeast an addition of T6 l nis 

 of 1 per cent, of pure alcohol retarded growth ma- 

 terially, proportionately much more than larger 

 amounts. Two pairs of puppies were experiment- 

 ed with, to one of which alcohol was given in non- 

 intoxicant doses, which were increased as the puppies 

 grew. Growth in both pairs continued practically 

 normal, the alcoholic pair even growing a little 

 faster than their controls at first. Each normal 

 puppy was. however, about 5 per cent, heavier than 

 its alcoholic brother or sister. On the side of the 

 reproductive faculties, too. the alcoholic pair proved 

 not inferior to the normals. The chief difference 

 was on the psychic side. Both the alcoholic ani- 

 mals were much quieter than their controls, and 

 both were abnormally timid. 



Interesting experiments in the synthesization 



