This laboratory notebook contains two sets of records which cover chicks hatched between April and June 1902. Each has a different W number sequence.

Entries begin with records for birds labelled W 866-999 [pp. 2v-132r] (which hatched between April and May 1902), followed by a new series for birds W 1-74 [pp. 133-190v] (hatched May to June 1902).

Of the second series, birds W 1-25 were originally given different numbers in the journal which were then replaced and in some cases excised. (The original numbers include the sequence W 687-699 which was skipped between notebooks MS Add.10161/1/1/8 and MS Add.10161/1/1/9).

Entries for each bird include notes on colour, comb and other physical characteristics or oddities (e.g. crooked toes), state of health, and cause of death, etc. Bird W 42 [page 172v] is marked 'important'. An additional loose list of chicks 'with/without [yellow]' is inserted between [pp.58-59].