4 
1908. | Minute Structure of the Nervous System. 429 
structure of the organ of sight, the retina, which is the less requisite as 
- Cajal described it in his Croonian lecture. 
As regards the termination of the sensitive and tactile nerves in the 
epidermis, the epithelia, and the specific sense organ, the Pacinian corpuscles, 
the Krause end-bulbs, etc., one may formulate a general rule as follows :— 
They terminate everywhere with free endings and. ramifications, though 
differing in arrangement in different cases, and sometimes among cells 
(Merkel’s terminal discs, Grandry’s corpuscles, etc.), which may, to a certain 
extent, be compared to secondary sensory cells. 
To give a survey of these different types of terminations I have drawn up 
a few diagrams of the various kinds of sensory cells (fig. 9). 
The olfactory cells and those sensory cells of the invertebrata that are here 
under discussion are consequently to be regarded as a kind of peripheral 
neurones, the gustatory and auditory cells on the other hand may not, strictly 
speaking, be so considered; the real neurones of the latter, as also of the 
terminal branches of the tactile nerves, are constituted by the nerve-cells 
situated in the cerebro-spinal ganglion system. | 
The neurone theory had consequently from a morphological point of view 
shown itself to be correct, both as regards the facts connected with the 
central organ and the peripheral one, and the Golgian method had yielded 
results agreeing in all essentials with those of the methylene staining one. 
The difference between our knowledge then and that we possessed, for 
instance, in 1880, was prodigious. Yet, in reality, it was a mere handful of 
investigators, dwelling far apart from one another, who had accomplished 
this work. In some quarters, even among eminent anatomists, physiologists, 
and especially neurologists, the work and results of those investigators were 
long regarded with a certain suspicion; now and then that suspicion found 
expression in a rather startling form. I might, for instance, read to you 
letters which I received from celebrated histologists abroad, who were other- 
wise favourably disposed towards me and my work, conjuring me in the 
most serious and moving terms not to go on experimenting with that 
wretched Golgian method which only resulted in art effects, impure chrome- 
silver precipitations within the tissues, and were misleading and dangerous 
for real scientific inquiry. Pretty much: the same verdict was pronounced, 
too, from a specially authoritative source upon the methylene method as we 
applied it. From the point of view of the history of science it may be 
of a certain interest to note that our labours by no means met with 
encouragement and recognition in all quarters. 
The new school of investigators found little difficulty in dealing with these 
antagonists. 
d, VOL. LXXX.—B. 2M 
