534 W. WOODLAND. 
The reason for the fact that the scleroblastic development 
of the Cucumarian spicule has not hitherto been ascertained 
lies in the considerable difficulties attending the investiga- 
tion, for, in the first place, most “siurefrei”’ plasma stains 
have but little effect on the cells contained in the Cucumarian 
body-wall, and hence, nuclei being alone visible, it is hard 
to say under these circumstances whether any scleroblasts 
exist at all; and secondly, supposing the first difficulty over- 
come, the spicules of most Cucumariide are so densely 
crowded in the thick body-wall as to render it in most cases 
impossible to determine which scleroblasts belong to which 
spicule, it being assumed that the observer has learnt to dis- 
tinguish scleroblasts from the several other histological 
elements of the body-wall. My own partial success in solving 
these difficulties was attained, firstly, by persistently experi- 
menting with various plasma stains (picro-carmine forming 
an excellent nuclear stain, as in the case of sponges, Alcyon- 
aria, etc.) until I happened to discover that which alone gave 
satisfactory results; and secondly, by patiently searching 
through scores of preparations of portions of Cucumarian 
body-wall, drawing only those comparatively few spicules 
concerning the entirety and individuality of which no doubt 
could be entertained. In calcareous sponges, e.g. most 
spicules are easily observable and can be drawn as distinct 
individuals, but in the Cucumariide which I have studied 
only about 5 per cent. of the spicules are so situated as to 
permit of their being correctly figured. In no case have I 
drawn a spicule about which any uncertainty existed as to 
the number of the attached scleroblasts. 
The method of preparation of the Cucumarian body-wall 
for high-power microscopic examination which I finally 
adopted was as follows:—The Cucumarias (not more than 
8 mm. in length, and some considerably less) were fixed, as 
in the case of calcareous sponges, etc., in 1 per cent. osmic 
acid for ten minutes, washed with distilled water and stained 
for three hours in picro-carmine (Ranvier’s or Weigart’s), 
washed again, and graded up to absolute alcohol (all strengths 
