PROGRESS OF MICROSCOPICAL SCIENCE. 75 



activity of the spinal cord only is called into play, and only a simple 

 reflexion results. The other sensitive fibres, on the contrary, pass 

 directly into the optic thalamus ; there the impressions undergo a 

 first relay ; then they are radiated by the converging cerebral fibres 

 towards the cells of the convolutions, when they become the materials of 

 the ulterior operations of the intelligence. The will, thus awakened, 

 enters into activity, and transmits, in its turn, its determinations 

 along the path of the converging fibres, especially the cortico-striate 

 fibres. The voluntary impulse thus arrives at the striated body ; it is 

 there reinforced ; thence sets out again along the cerebral peduncles 

 and the grey axis of the cord, and finally proceeds to excite the roots 

 of the motor nerves, and to determine movement. As to the cerebellar 

 apparatus placed at the confluence of the cerebral and spinal systems, 

 it constitutes a sort of reservoir of nervous influence — an influence 

 which appears to spread itself incessantly along the anterior spinal 

 system, and to expend itself in answer to each appeal that reaches it 

 from the superior voluntary centres. In the normal state, the distri- 

 bution of the cerebellar influx in each half of the body maintains the 

 physiological equilibrium. If this uniform distribution be disturbed, 

 there appear immediately incoordinated movements, blind and irre- 

 sistible influence, vertigo, and a veritable titubation. 



Is the Source of Ague discovered ? — Dr. Salisbury, of the United 

 States, thought it was proved by him some years ago,* by his remark- 

 able discovery of the malarial essence in the cells of certain Palmelloid 

 plants. Desiring to investigate the subject, Dr. John Bartlet says that 

 he sought for the plants described by Dr. Salisbury, in the ague bot- 

 tom of the Mississippi River, opposite Keokuk, Iowa, lat. 10° 25'. Not 

 being provided with a suitable microscope, he was unable to discover 

 the microscopic algas described by the Doctor. He was pleased, how- 

 ever, to find the fungi, samples of which he has sent to Mr. Cooke, the 

 editor of the Journal to which he addresses his letter. Generally it 

 answers Salisbury's description. It does not correspond in these im- 

 portant particulars : Salisbury's plants are so minute that it requires a 

 powerful lens to render them visible. A single specimen of plant may 

 be discovered as you stand. Salisbury's plants were not less (?). These 

 have roots \ or T 3 ^ of an inch in length. They grow on the flat moist 

 alluvium of the slough and river margins and their drying beds ; in the 

 vicinity of such localities they may be found on ordinary soil in damp 

 places, even at some elevation. " The specimens sent you are green ; 

 I have observed them slate-coloured, pink, and black. They vary in 

 size from a mere point to -^ of an inch in diameter. When in natural 

 state they are globular in shape and of a fresh colour ; when covered 

 with water they swell and present a gelatinous appearance. They 

 discharge their spores when ripe by slitting open at the top, and a 

 falling in, collapsing of the upper circumference : so that a discharged 

 plant appears cup-shaped, and to the naked eye it seems to have lost 

 the upper half of its circumference. So far as I have been able to 

 determine with the imperfect means of observation at my command, 



* ' American Journal of Medical Science,' 1866. 

 VOL. IX. G 



