Vol. XXIX August, 1915. No. 2 BIOLOGICAL BULLETIN SEXUAL REACTIONS BETWEEN HERMAPHRODITIC AND DKECIOUS MUCORS. 1 ALBERT FRANCIS BLAKESLEE. CONNECTICUT AGRICULTURAL COLLEGE, STORRS, Coxx. INTRODUCTION. Conjugation among the Mucors has been assumed to repre-sent the simplest type of reproduction acknowledgedly sexual in character. Some even have denied the term sexual to the union of morphologically similar gametes such as occur in this group. The present article will present further evidence in favor of the author's contention that although the process is morphologically a simple one, conjugation in the Mucors is as definitely a sexual process as the morphologically more complex type of reproduction in higher forms and that the sexes seem even more sharply distinct. It has been shown by the writer ('04, '09) that the majority of the forms among the Mucors are dioecious, with the sexes separated in male and female races which are capable of being propagated apparently to an indefinite number of vegetative generations by means of nonsexual spores formed in sporangia. In all the dioecious species carefully investigated the opposite gametes, which are produced and unite to form zygospores when the two sexual races of a given form are grown together, do not appear to differ morphologically. Lacking a definite criterion which an inequality of the gametes would have afforded, the writer has provisionally designated the opposite sexes in these forms by the signs ( + ) and ( ) on account of a generally greater vegetative luxuriance of one sex over the other. That 1 Report of investigation carried on, 1912-13, at the Carnegie Station for Experimental Evolution, Cold Spring Harbor, N. Y. 87
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