Fig. 2. ¹³C values (mean ± s.e.m.) of inseminated (open triangles) and uninseminated (bold line) spermathecae from experiment 2. For labelling treatments see Fig. 1. The mating and dissection history of each treatment is illustrated in the lower part of the graph. Duration of mating if longer than 1 night is indicated by arrows; Female symbol with a pin indicates spermathecae dissection. Subdivisions A–C refer to different batches of males (see text). N, number of samples analysed for inseminated (+) and uninseminated (–) spermathecae. Dotted line indicates the threshold value of 3 s.d. above mean ¹³C of virgin females. Virgin (V) and standard (St) samples are included. Virgins are uninseminated females from treatment U–U. Value excluded from analyses: –13.02 (A,L–U). Values with different letters are significantly different at P<0.05 for I (lower case), or II (upper case) in A. Planned contrasts (P<0.05) in B were made between the three values, and in C between the four values. Asterisks indicate significant difference between positive and negative spermathecae at *P<0.05 and **P<0.01.