despite his contributions, de graaf made a number of errors in addition to believing that the ovum was the follicle. he never actually consulted the ancient texts but merely repeated the accounts of others compounding their inaccuracies. because he observed rabbits rather than humans, he assumed fertilisation took place in the ovary. he believed that the seminal vesicles stored spermatozoa. he was not yet aware of the presence of spematozaoa as such; these were discovered just after his death by the amsterdam student johannes ham, using the microscope of antonie van leeuwenhoek. based upon his rabbit experiments and the description of an ectopic pregnancy in a lady that had died in her 12th pregnancy in paris, he assumed that the complete entity was present in the ovary, brought to life by the influence of the male ejaculatory fluid, and then transported to the uterus.