THE EXTENSION OF THE PRINCIPLE. 105 
that the plant would not have suffered had light 
been admitted through the covering which pro- 
tected it from the cold ; and this could easily have 
been effected by means of melon lights, &c. 
6. To determine various important points re- 
specting those numerous and highly interesting 
tribes of plants and animals which, from their 
extreme minuteness, or fugacious nature, have 
hitherto eluded observation, but which the na- 
turalist in his study will now be enabled to 
watch, microscopically if required, during the 
whole period of their growth. Let the man of 
the world despise, if he will, these inquiries. 
There is nothing little in Nature, save those 
little minds which are unable to comprehend 
great truths# These microscopic objects — 
66 To us invisible, or dimly seen. 
. . . . Yet these declare 
Thy goodness beyond thought, and power divine.” 
In a work like this, it is impossible to enter 
into any lengthened detail respecting this mighty 
world of wonders. There is one class, however, 
which has excited in no small measure, the atten- 
tion of naturalists — I mean those small algce, 
whose reproductive spores, escaping from the 
parent plant, appear to be endowed with volun- 
tary motion, swimming about until they reach 
