Journal of experimental zoology . distribution of head-lengths of 993 sper-matozoa from same left testis as the one in figure 25. Value in M Frequency 1 2 7 9 13 19 47 48 103 112 111 109 99 89 81 61 47 21 15 10 2 4 3. »0 CC ^CO c<ic<i(Mc«c^cccocccoe»3cocoeococo Fig. 27 Anasa tristis; frequency distribution of head-lengths of 444 sper-matozoa from left testis. Valucinii 26 0 Frequency 1 6 11 19 26 37 53 36 63 63
Journal of experimental zoology . distribution of head-lengths of 993 sper-matozoa from same left testis as the one in figure 25. Value in M Frequency 1 2 7 9 13 19 47 48 103 112 111 109 99 89 81 61 47 21 15 10 2 4 3. »0 CC ^CO c<ic<i(Mc«c^cccocccoe»3cocoeococo Fig. 27 Anasa tristis; frequency distribution of head-lengths of 444 sper-matozoa from left testis. Valucinii 26 0 Frequency 1 6 11 19 26 37 53 36 63 63 64 41 20 6 3 2 2 0 0 1 SIZE DIMORPHISM IN SPERMATOZOA 217 (d) Condusion. Nine of the ten sets of measurements showvery distinctly a bimodal distribution. The one unimodal setagrees very closely with the upper group of a bimodal set. Con-sidering the evidence as a whole there is no escape from theconclusion that there are two principal size groups among thespermatozoa of Anasa tristis. The high points in nearly allthe cases come at essentially the same places in the differentmeasurements, though there is considerable variation in the two size groups are dependent upon chromosomaldifferences is made very probable by a comparison of the observedand expected ratios. The two modes
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1904
