Dec. ii, 1879] 



NATURE 



14; 



The Parotid Gland of the Rabbit. — The alveoli of the gland 

 can be observed in the living state without serious interference 

 with the blood circrlarion. When the gland has been quiescent 

 for several hours, the alveolar-cells are granular throughout, and 

 the outlines of the cells are only faintly marked as clear lines with- 

 out granules. When the gland secretes, the granules disappear 

 from the outer borders of the alveolar-cells, that is, from that por- 

 tion of the cells nearest the basement membrane. After prolonged 

 secretion, very few granules are left in the cells ; those that do 

 remain in any cell form a thin layer at its inner portion, that is, 

 at the portion bounding the lumen, and stretch outwards, also 

 as a thin layer, along the cell-sides a variable distance from the 

 lumen. 



In an alveolus during secretion, the cells separate from one 

 another slightly near the lumen ; thus the lumen stretches out for 

 a short distance between the cells ; it becomes larger, at the 

 same time, by the diminution which takes place in the size of the 

 cells. 



The above described changes occur whether the secretion is 

 induced by giving food to the animal, or by giving it pilocarpin, 

 or by stimulating the sympathetic nerve running to the gland. 

 The two zones of the fresh state are not preserved by alcohol 

 and other reagents. 



Osmic acid shows some considerable differences between the 

 resting and the active gland, the chief amongst which is the 

 more equal staining of the substance of each alveolar-cell in the 

 active state. 



The Parotid Gland in the Rat, Cat, and Dog behave in rest 

 and activity like the parotid of the rabbit in a corresponding 

 condition. The living condition in these cases, however, has 

 not been observed in the glands with intact blood-circulation. 



In one case where the sympathetic nerve of a dog was stimu- 

 lated, a saliva was obtained from the parotid, of unusual cha- 

 racter. The saliva clotted readily, and contained 8'3 per cent, 

 of solids, of which 7'S per cent, were organic substances. 

 Jacobson's nerve was uncut. The much more rapidly flowing 

 saliva following subsequent injection of pilocarpin had a slightly 

 lower percentage of salt than the slowly secreted sympathetic 

 saliva. In several cases in other glands I have also seen a 

 diminution in percentage of salts, notwithstanding an increased 

 rate of secretion of fluid. 



The Sub-maxillary Gland of the Rabbit undergoes changes in 

 activity similar in the main to those which occur in the parotid. 

 The changes are, however, less marked ; the granular condition 

 of the gland ha? a less direct relation to the state of hunger of 

 the animal. 



The sub-maxillary gland has one very characteristic feature, 

 the transition- and some of the ductule- cells contain, in life, 

 granules more distinct and larger than those contained in the 

 alveolar-cells. How far these disappear during secretion is 

 uncertain. 



As in the parotid so in the sub-maxillary, reagents do not 

 preserve the normal appearances. The secreting gland treated 

 with osmic acid shows alveolar-cells much more evenly stained 

 throughout than does the resting-gland. 



The deep black staining of the transition-cells with osmic acid 

 described by Nussbaum does not take place if the gland be 

 treated with osmic acid only ; the deep coloration is the result 

 of a subsequent treatment with alcohol. With osmic acid alone, 

 the ducts stain darker than any other part of the gland. 



I must uphold my previous objection to Nussbaum's view that 

 ferment is formed in the transition-cells and not elsewhere. 

 Briefly my objections were that the ductule-cells, in their method 

 and depth of colouring behave like the transition-cells, and that 

 the black coloration of the transition-cells with osmic acid does 

 not occur if the gland is previously treated with absolute 

 alcohol, in which the ferment is said by Nussbaum to be in- 

 soluble. 



I can in the main confirm Bermann's description of a "tubular 

 gland " in the sub-maxillary of the rabbit. 



The Infraorbital and Lachrymal Glands of the Rabbit show 

 an outer clear and an inner granular zone in activity even more 

 distinctly than the parotid. In both these glands osmic acid 

 preserves more nearly the living appearances. The two zones 

 if present normally, are also present after treatment with osmic 

 acid. 



In the Mucous Glands during secretion the changes in life are 

 less readily followed, but they are probably similar to those 

 mentioned above. In rest the alveolar-cells form granules like 

 the alveolar-cells of a serous gland ; but in the former case the 

 granules are of nearly the same refractive power as the sur- 



rounding substance and so not conspicuous. In activity the 

 granules are used up, and disappear first from the peripheral 

 parts of the cells. 



" Report on Phyto-Palxontological Investigations on the Fossil 

 Flora of Sheppey." By Dr. Constantin Baron Ettingshausen. 

 Professor in the University of Graz, Austria. Communicated 

 by Prof. Huxley, Sec. R.S. 



Physical Society, November 22.— Prof . W. G. Adams in the 

 chair. — New Members, Prof. Reilly and Prof. Heath, of 

 Cooper's Hill Engineering College. — Prof. Guthrie exhibited a 

 new photometer in its crude form and demonstrated its action to 

 the meeting. It consists of two fixed plane mirrors inclined to 

 each other at an angle. The rays from the two sources of light 

 to be compared, are allowed to fall on these mirrors, those from 

 one source, say that on the right hard, falling on the right hand 

 mirror, and those from the left hand source on the left hand 

 mirror. These rays are again reflected from the mirrors at right 

 angles to their former paths and thrown upon a semi-transparent 

 screen where their relative intensities can be compared by the 

 eye of the observer between the mirrors and each source of light ; 

 a revolving shutter is interposed. These shutters are formed of 

 brass disks and they are both mounted on the same axis which 

 can be turned by hand or otherwise. They would completely 

 screen the light from the mirrors were it not that each is provided 

 with four radial apertures or slots through which the rays can 

 pass. The slots on the side at which the brighter source of light 

 is placed are narrower than those on which the weaker source is 

 placed. The latter slots are made adjustable in size by sliding 

 blinds and a scale is added to measure the degree to which they 

 are closed. On revolving the shutters the reflection of the rays 

 to be compared are seen side by side and (owing to persistence 

 of images on the retina) continuously on the screen placed in 

 front, and they are brought to equality of brightness by closing 

 or opening the blinds of the adjustable shutter. When this is so 

 the ratio of the respective orifices of the shutter as given by 

 the scale is the inverse ratio of the luminous intensities compared. 

 Prof. Adams remarked that the speed of rotation should be 

 such as to produce a uniform field of light on the screen, a result 

 which hand-turning was not very conducive to. Prof. Foster 

 observed that the use of this new photometer might be less 

 fatiguing to the eye than those photometers which presented a 

 steady beam to the eye undiluted with intervals of darkness during 

 which the light is cut off, as on the instrument before the meeting. 

 — Prof. Keinhold then read a paper by Prof. Riicker of the York- 

 shire College, Leeds, on a suggestion as to the constitution 

 of chlorine offered by the dynamical theory of gases. If a 

 gas of density 8 consists of molecules each of which possesses 

 no de<nees of freedom, and if also the inter-molecular forces are 

 negligable, the specific heats at constant pressure (Cp) and at 

 constant volume (Cv) are connected by the two well-known 

 equations, 



(1) (Cp-Cv) S = -0694 



(2) Cp ... I + 2 

 ~Cv 111 + e 



where e is a quantity which depends upon the potential energy 

 of a molecule ; hence if Cp is given by experiment Cv can be 

 calculated from the first equation, and then in + e is known 

 from the second. Regnault determined the specific heats at con- 

 stant pressure of 35 gases, and from the experiments of E. Wi-nde- 

 mann and of Wullier it appears that his values are correct within 

 6 per cent., and that m + e can be calculated very approximately 

 from the above equations if Cp is given. One of the chief difficul- 

 ties of the thermo-dynamic theory of gases has been to attribute 

 to m and e values which would at once lead to the observed 1 

 of Cp and Cv and satisfy any rational supposition as to the 

 interior mechanism of a molecule. Kundt and Warhng proved 

 that for mercury £ = I '666, which is consistent only with 



the supposition that the atoms of mercury are smooth rigid 

 spheres ; and Boltzman and Bosanquet have pointed out that for 

 a smooth rigid surface of revolution -/ = 1-4, a number agree- 

 ing closely with the experimental value for air, O, N, H, CO and 

 NO. The molecules of these gases may therefore be constituted 

 of two spheres rigidly united, or, as Prof. Rucker suggests, bound 

 together by forces which prevent their separation of their surfaces 

 while leaving them otherwise free to move. The principal 

 object of Prof. Rucker's paper was to point out an interesting 

 fact connected with the application of this theory to chlorine. 



