1889.] Microscopy. 277 
and the readiness with which ideas recur. In a previous re- 
port in the Proceedings {ante, pp. 86) I have shown that even 
in so indifferent a matter as the ten digits, there are uncon- 
scious preferences of the mind, or, in other words, that the 
notions or images of certain digits come forward oftener and 
more readily than of others ; and I have also shown ante, pp. 
90-91, that the order of relative frequency is similar for differ- 
ent persons. It is probable that all ideas possess each its 
special degree of readiness of appearing in consciousness, and 
that the degree of readiness is approximately the same for a 
great many persons. This similarity probably also prevails 
in regard to the majority of ideas. 
This aspect of our mental processes puts the problem of 
thought-transference in a somewhat different light from that 
in which we have been asked to view it. It is evident that if 
two people are requested to think of some one thing as a class, 
such as a letter of the alphabet, a playing card, a baptismal 
name, there is by no means an equal chance of their selecting 
any one ; on the contrary, there is not only the probability 
that they will think of a special one first, but there is a chance 
of their both thinking of the same one, for the relative fre- 
quency or preponderance of one idea or image out of a set has 
been shown to be similar for a number of people. In order to 
prove the reality of thought-transference, it must be demon- 
strated that the observed coincidence of thoughts can not be 
explained by the law of relative frequency. — From Proceed- 
ings of the Society of Psychical Research. 
MICROSCOPY.' 
The Culture of Infusoria.' — Damp chambers. The first 
requisite in the culture of infusoria is suitable damp chambers, 
constructed with a view to reducing the evaporation of the 
water of the preparations to a minimum. Evidently, bell-jars, 
admitting a large volume of air, will not serve the purpose. 
I-o\v, flat-bottomed dishes, with vertical sides, and about 20 
cm. in diameter, are recommended. The dish is partly filled 
with fine, well-washed sand, and in this are planted longitud- 
inally two upright strips of glass, of such a height that the 
superior edge is 4 or 5 mm. below the level of the edge of the 
dish. 
On these upright pieces as supports are placed three others, 
