CHAIN OF CYCLOSALPA AFFINIS 443 
We conclude with an acknowledgment of our indebtedness to 
the work of several other biologists who have entered by one or 
another gate the course upon which we find ourselves. Of these 
perhaps the first to be mentioned is Julius Sachs whose idea of the 
grand period of growth in plants must, it seems to us, expand and 
play a much larger role in biological theory in the future than it 
has in the past. After Sachs, chronologically, the various inves- 
tigations by C.S8. Minot on the rate of growth in aminals has largely 
influenced our observations and thinking. Another research, 
that by T. Tammes entitled ‘‘Die Periodicitiét morphologischer 
Erscheinungen bei den Pflanzen,” has had considerable to do with 
shaping our ideas on the strictly biological side. But by far the 
most important as opening up the way to the quantitative work 
has been Raymond Pearl’s ‘Variation and Differentiation in 
Ceratophyllum.’”’ Although Pearl’s quantitative data in this 
research are entirely enumerative rather than mensural; and 
although his aims and results are in several rather important 
particulars different from ours, his fundamental problem really 
gave us our starting point. 
JOURNAL OF MORPHOLOGY, VOL. 22, NO. 2 
