It needs an explanation why among the botanical papers published in this volume to honour Mrs. Weber—van Bosse on her 90th birthday a zoological contribution has been inserted. Those who have read the curriculum vitae of this wellknown botanist in the foregoing pages of this volume will not wonder, for they know that she has been keenly interested for more than half a century in the zoological work of her late husband. And so among the chorus of botanists the voice of a zoologist could hardly be missed. For many years I have enjoyed the friendship of both, and I am grateful for this opportunity to show Mrs. Weber my affection and my admiration. When contemplating an adequate theme for this paper it occurred to me that in some way or other it had to dwell on the relations between zoology and botany and as the distribution of animals is a branch of science which has always interested both Max Weber and me, I decided on the influence which the distribution of plants has on that of animals.