Transmission of Infra-red Rays and of Radiant Energy. 7 1 



processes of the ciliary body themselves. A rise of temperature of the pig- 

 ment layer due to the absorption of heat must necessarily cause at the same 

 time a rise of temperature by conduction to surrounding structures, in this, 

 the glandular elements of the ciliary body take part. 



Secondly, the very intimate relationship that exists between the arterial 

 supplies of the iris and ciliary processes may be mentioned, both coming off 

 as branches from the circulus arteriosus major. It is possible that the 

 lymphatic drainage is no less intimate, it is also conceivable that the vaso- 

 motor nerves to these arteries also send glandulo-motor nerves to the ciliary 

 processes ; on these points, however, we have only the evidence of analogy 

 with other secretory organs. 



There are several remarkable features in the occurrence of glassmakers'" 

 cataract ; the very long period taken for the condition to develop does not at 

 all suggest any pathological change of an inflammatory nature, neither has 

 any obvious change in any other structure of the eye apart from the lens been 

 described. Thus the pupil is normal in size and reaction to light, which would 

 not be the case if it had been the seat of any chronic inflammatory change. 

 It would seem to us more likely therefore that the change in nutrition of the 

 lens is one brought about by some physiological alteration in the secretory 

 mechanism of the aqueous rather than to a pathological change. We have 

 only to postulate a secretion of aqueous when heat falls on the iris to obtain 

 what appears to be a plausible hypothesis of the formation of the cataract. 

 Normally aqueous is secreted in small amounts all the time ; when heat falls 

 on the iris a larger secretion occurs, which is followed when the stimulus stops 

 by a period of rest. This stimulus, falling regularly for long periods, in time 

 causes the secretory mechanism to be more and more dependent on the 

 external stimulus. The secretion becomes periodic in character and, instead 

 of the lens receiving nourishment all the time, it only receives it at intervals, 

 with the result that the least well nourished part of the eye suffers and 

 cataract develops. 



Whether or not the heat absorbed by the iris stimulates the secretion of 

 aqueous humour, and how it stimulates it, whether by rise of temperature, 

 vaso-dilatation or actual reflex stimulation, experiment alone can show. Our 

 object in mentioning the matter here is that it seems to us to offer a feasible 

 line of attack for future investigation. 



Protection of the Eye from Harmful Radiation by Crookes Glasses. 

 In order to protect the eye from damage by the radiation from luminous 

 bodies, it is necessary to remove as completely as possible the ultra-violet and 

 infra-red rays, for these, while taking no part in the vision of external objects. 



