Slide showing diagram of 'Chromosones of the plant bug Protenor'. Slide shows black and white diagram of 'Chromosones of the plant bug Protenor'. Title below diagram reads 'Fig. 77. Chromosones of the plant bug Protenor'. Key to symbols below diagram reads '(1) Of female. (2) Of Male. (3) The reduction division in the male (See (5) of Fig. 73). (4) Male determining and (5) Female determining sperms, resulting from the unequal division in (3).' Late 19th - early 20th century